# IS it safe to use 89 Octane instead of 93 at my local US gas station??



## rebchief (Mar 17, 2007)

nm


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## Turbocrazy (Nov 14, 2002)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*

This always seems to spark a debate, but here's my thoughts. I wouldn't recommend consistently using 89 octane. The engine has knock sensors and will advance/retard the timing so as not to ping and knock on 89. But I think its been stated that doing this for the life of the engine can cause premature wear. I think a turbo engine is more susceptible as well. Also, if something were to go wrong internally with the engine, I believe a dealer can test what octane fuel is in the tank and possible bring up warranty concerns.
Also, when an engine is running on an octane lower than what it was designed for, the changing of the timing essentially robs some horsepower. To maintain similar driving speeds, you would essentially be running less efficient, probably negating any money saved by using the cheaper fuel. I would stick with what's recommended and leave it at that. Just my 2 cents.


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## rebchief (Mar 17, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (Turbocrazy)*

Sounds great. Thanks!!


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (Turbocrazy)*

Turbo has already given you a comprehensive answer.
The owners manual recommends that premium grade fuels are used but also states that 89 octane (regular) fuel should not cause any damage to the engine , but will affect performance.
I read this as: Use premium fuel, but if you find yourself with an empty tank and no premium fuel available, you don't have to fret about running a tank or two of regular through the engine.
Kevin










_Modified by just4fun at 11:09 AM 3-22-2007_


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*


_Quote, originally posted by *rebchief* »_IS it safe to use 89 Octane instead of 93 at my local US gas station??

The answer to the question can be found on the inside of the gas flap of the car. The sticker shown below is a European sticker, so don't use it, instead, go open your own gas flap and see what it says there.
Michael
*Where to find the gasoline grade specification for the car*


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

To update further:
As per Micaels post the sticker inside the fuel door states Premium Fuel Only 91 AKI.
The owners manual, as per the image below, gives specific info regarding Octane Rating and Fuel Blends. It states not to use fuels with Octane Ratings of less than 87 AKI or damage to engine may occur.
I guess we have to decide which documentation is accurate, the sticker or the owners manual.
I still read it: use premium, but if premium is not available, a tank of regular isn't going to damage anything.
*NOTE: Canadian Owners Manual: NAR should be similar, but check your owners manual to confirm.*








Kevin










_Modified by just4fun at 6:04 PM 3-22-2007_


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*


_Quote, originally posted by *just4fun* »_...the sticker inside the fuel door states Premium Fuel Only 91 AKI.
The owners manual... states not to use fuels with Octane Ratings of less than 87 AKI or damage to engine may occur.
I guess we have to decide which documentation is accurate, the sticker or the owners manual.

Guys and Girls:
Both numbers are correct. The problem is this: There are quite a few different systems available to measure the resistance of any given motor fuel to pre-ignition (detonation, knocking), exactly the same as there are quite a few different systems out there to measure the point at which water freezes.
In the United States, water freezes at +32°.
In Canada and Europe, water freezes at 0°.
But, if you ask a scientist (Canadian, American, or European, doesn't matter) what temperature water freezes at, he or she might tell you that it freezes at 273°.
The damn water is the same everywhere and it freezes at the same temperature everywhere. The problem is that the Americans are using Fahrenheit, the Canadians and Europeans are using Celsius, and the scientists are using Kelvin as their "measuring index".
I know for sure that there are two commonly used octane measuring indexes - RON (Research Octane Number) and (R+M)/2. However, it now seems that there are two different names - (R+M)/2 and AKI - for the same measuring index, exactly like there are two different names for the Canadian and European temperature measurement system, which can be called either Celsius or SI, as you prefer. So it looks like there are three systems when in reality there are only two commonly used systems.
Wikipedia appears to have a good article that explains the different octane measuring indexes. Click here to read it, it will help you sort the mess out and understand what the alphabet soup is. After you read that, you can go read this thread in the Phaeton forum: Fuel Octane Specifications for the Phaeton (includes TB 01-06-02, Fuel, Poor Quality), which further hashes the subject out and includes an interesting Technical Bulletin from VW about fuel quality.
Michael


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_
So it looks like there are three systems when in reality there are only two commonly used systems.
Michael

Thanks Michael, for once again providing additional clarification. I had previously read an article on octane ratings and, since I was already familiar with the differences, I didn't think to provide clarification on the different standards.
Discussion:
The Owners manual states that the _*recommended*_ octane rating is listed on the sticker inside the fuel door. Which on the Canadian Spec Eos is listed as minimum 91 (AKI or (R+M)/2 or "octane")
The owners manual also states that you _*may*_ use fuels with 87 or higher (AKI, (R+M)/2, or "octane") rating.
In a manner similar to "*recommend* servicing at a certified VW dealership" vs. "you *may* choose to do your own routine maintenance", it comes down to interpreting the verbage in the owners manual.
Personally I will always use the best premium fuel available, but if I'm in a bind and have no choice, I'll put regular in and not be concerned about it.
Kevin











_Modified by just4fun at 7:43 PM 3-22-2007_


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## mark_d_drake (Aug 17, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*

US Spec 3.2L


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*

The question of 'recommended' vs. 'permitted' fuel grades is almost as controversial a topic as what oil to use, what religion to practice, or what political party to vote for. I'm going to try and present a very neutral overview of past discussions of this topic here:
*1) Electronic Engine Control:* All VW products built since the early 1990s use electronic engine controllers. Amongst other things, the engine controller monitors pre-ignition (knock, detonation) by using dedicated knock sensors attached to the engine. If pre-ignition is detected, the electronic controller makes adjustments to the engine timing and other variables that it can control to eliminate the pre-ignition problem. This will inevitably lead to reduced performance. Sometimes, this reduced performance is acceptable to the engine designers, and sometimes, it is not.
*2) Reduced Performance:* ...is not necessarily a bad thing. For example, I have a 420 HP 12 cylinder engine in my VW. The owner manual states that premium grade fuel (91 octane, using the common North American measurement) is the preferred fuel, but that it is perfectly acceptable to use 87 octane fuel if the owner is willing to accept reduced performance (translation = reduced horsepower). I have found through experience that I don't really need all 420 horsepower to drive down to the grocery store to buy a jug of milk, so, occasionally I just fill the thing up with regular grade (87 octane) fuel, and the car works OK. I can notice when I have been using regular grade for several tankfuls, though - the car is not quite as snappy as it usually is.
*3) 'Preferred' vs. 'Recommended':* There is a very critical nuance that we have to pay attention to, and that is the issue of 'preferred' fuel grade and 'recommended' fuel grade. Some Volkswagen engines - my W12 being a good example - are engineered to run on a fairly wide range of octanes. If you have a look at the Phaeton W12 gas cap sticker below, you will see that the gas cap sticker shows a range of grades - this appears as the *91 / 87* marking on the gas flap. If you see two grades on your gas flap like this - *both with equal prominence* - then the higher of the two is the 'preferred' grade, but the lower of the two is perfectly acceptable, provided you are willing to accept the lower performance. In other words, I could run the engine on 87 octane all the time, and never ever encounter any engine problems. 87 is fully acceptable for my engine.
BUT... not all engines are designed to run on a range of octanes. Although both 91 and 87 are fully approved for the Phaeton W12 engine, the gas cap sticker for the V8 powered Phaeton is very different - it shows only one number on the gas cap sticker, and that is 91 octane (premium fuel). The V8 owners do not have the choice of using regular grade fuel as an alternative to super... the specification for the fuel for that engine is super (91), plain and simple. Lower octane fuel should only be used in an emergency. 
Sadly, I don't have a picture of a V8 Phaeton sticker that I can attach here to show you the difference between the W12 fuel specification (91 preferred, 87 acceptable), and the V8 fuel specification (91 recommended, lower grades for emergency use only). I do have a picture of a European fuel cap sticker from a car with an unknown engine that shows that 98 octane (on the European scale) is the recommended fuel (note that all the text says "super plus" very clearly), and 95 octane (on the European scale) is the emergency alternative - note how the 95 number is much smaller, and in parentheses. Sorry about mixing up measurement systems (European and North American) in this example, but these photos are all I have available.
--------------------------------------
I think that they key point here is to look carefully at the sticker on your fuel cap, and endeavour to determine whether the auto manufacturer is giving you a choice between fuel grades that are all fully acceptable, or whether the auto manufacturer is clearly recommending one specific fuel grade as the fuel that you should use.
Lastly - you will not gain any benefit from using a higher octane rating than the automobile manufacturer specifies, no matter how hard the various gasoline retailers try to convince you otherwise. In my case, the highest octane number specified for my W12 engine is 91 on the American scale. If I put 93 in the car, it won't perform any better - I'm just wasting my money.
Michael
*Fuel Sticker giving owner a choice of equally acceptable fuel grades*
_(North American W12 VW Engine, 2004 'BAP' version of engine, 420 horsepower)_

*Fuel Sticker giving owner a choice of equally acceptable fuel grades*
_(European W12 VW Engine, 2008 'BTT' version of engine, 450 horsepower)_ - note that as engine is upgraded, fuel specifications can change!

*Fuel Sticker clearly specifying that 98 RON is the recommended fuel*
_(unknown engine of a European car)_



_Modified by PanEuropean at 6:38 PM 3-23-2007_


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (mark_d_drake)*

This sticker is pretty clear and unambiguous - you *must not* put anything less than 91 octane (American measurement system) into the fuel tank, except possibly in an emergency. If you have an emergency, go to the owner manual to see if there is further guidance published there.

_Quote, originally posted by *mark_d_drake* »_US Spec 3.2L


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*


_Quote, originally posted by *PanEuropean* »_
I think that they key point here is to look carefully at the sticker on your fuel cap, and endeavour to determine whether the auto manufacturer is giving you a choice between fuel grades that are all fully acceptable, or whether the auto manufacturer is clearly recommending one specific fuel grade as the fuel that you should use.


Michael,
Before I start I want you to understand I hold your opinions and knowledge of VW products in the highest regard. But I don't entirely agree with your interpretation of the available information.
Forum members often tout RTFM (read the fine manual) as a reliable source of information on your particular automobile. The owners manual, as posted above, specifically references the information on the fuel door sticker as a recommended (or preferred) fuel. (the sticker on the Canadian Eos identifies 91, I'll post a picture later)
The terms "recommended" or "preferred" or "suggested" are not definitives. Had the manual indicated "restricted" or "required" or "only" this would specifically indicate there are no alternatives, or other choices.
The owners manual further goes on to identify several fuel alternatives that "may" also be considered for use in the Eos. 
The owners manual specifically states that only if you use fuels with "octane" ratings below 87 is there a concern of resultant engine damage.
I think a reasonable interpretation of the information supplied on both the fuel door sticker, and the owners manual, clearly identifies a range of fuels acceptable for use in the Eos.
I'm not sure about Ontario, but during my travels in and around Alberta, BC and the Northern States I have learned that premium fuels are not always available once you wander off the beaten track.
If the Eos "requires" premium fuels, or a risk of engine damage is present, then it is not a suitable vehicle choice in certain regions of North America. (and I don't believe that)
I'm not trying to pee in your cornflakes here, but I think a reasonable interpretation of the information is that premium fuels are "recommended" or "preferred", but fuels that meet the criteria identified in the owners manual and have octane ratings over 87 are "acceptable" for use.
Kevin


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## EOSmage (Feb 9, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

My understanding of this is that the engine was "tuned" to perform at its "best" when using the rated fuel listed on the inside of the Gas Cover. The manual states that the car will not be damaged by using lower grade fuels (above 87) but that the engine should not be expected to deliver top performance. 
A car manufacturer would be committing suicide if they created a car with an engine that imploded when used with available fuels in the sales region. For this specific reason, it is very hard to fill an "unleaded" tank with "leaded" fuel-- the filler hose doesn't fit easily into the tank. This "different sized hose" was designed specifically for my parents, who wouldn't know leaded from unleaded... or 91 octane from 150 aviation fuel. 
In a conversation today with my mother-- I just had to ask her directly-- she said: "Octane? I just push the button with the prettiest colour". What that means is, she doesn't have any idea if the "red backed 91 octane" is what the car needs, just that "red matches her car" and is the button she pushes.
I am confident that they are NOT saying that your warranty will be void if you use anything other than premium. I am confident that the cars engine will continue to purr just as long by using the lower octane gas. They have to build these cars to survive my parents, after all.
--[ that being said, my baby will only get premium... ]--











_Modified by EOSmage at 11:21 AM 3-23-2007_


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (EOSmage)*


_Quote, originally posted by *EOSmage* »_My understanding of this is that the engine was "tuned" to perform at its "best" when using the rated fuel listed on the inside of the Gas Cover. The manual states that the car will not be damaged by using lower grade fuels (above 87) but that the engine should not be expected to deliver top performance. 
A car manufacturer would be committing suicide if they created a car with an engine that imploded when used with available fuels in the sales region. For this specific reason, it is very hard to fill an "unleaded" tank with "leaded" fuel-- the filler hose doesn't fit easily into the tank. This "different sized hose" was designed specifically for my parents, who wouldn't know leaded from unleaded... or 91 octane from 150 aviation fuel. 
In a conversation today with my mother-- I just had to ask her directly-- she said: "Octane? I just push the button with the prettiest colour". What that means is, she doesn't have any idea if the "red backed 91 octane" is what the car needs, just that "red matches her car" and is the button she pushes.
I am confident that they are NOT saying that your warranty will be void if you use anything other than premium. I am confident that the cars engine will continue to purr just as long by using the lower octane gas. They have to build these cars to survive my parents, after all.
--[ that being said, my baby will only get premium... ]--








_Modified by EOSmage at 11:21 AM 3-23-2007_

x2
Kevin


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*


_Quote, originally posted by *just4fun* »_The owners manual specifically states that only if you use fuels with "octane" ratings below 87 is there a concern of resultant engine damage.

Hi Kevin:
I hear what you are saying, and I do respect your opinion too.
What perplexes me is the difference between the fuel spec for the Phaeton W12 and the Phaeton V8. These are the two cars I am most familiar with, partially because I own one, and partially because I have moderated that forum for a long time.
The fuel sticker (and manual notes) for the two engines are very different. The W12 owners have a choice of regular or super (not super plus, but just plain old super), but the V8 owners don't have that choice - they are told to use super, and that is the only number specified on the fuel flap.
What we don't know is how the engine people make the judgement call between 'recommended' and 'preferred' - or between 'use this or else' as opposed to 'this is the best'. It could be related to emissions, it could be related to what kind of performance drop-off takes place as knock resistance decreases, or it could be something else entirely that we have not considered.
I don't think it is unreasonable for an automaker to offer a vehicle for sale in North America that *requires *(imperative implied) 91 octane fuel. It might be a bit of a stretch to offer an engine that requires 93, because 93 is not always available, even in populated areas. I think, though, that you can get 91 octane just about anywhere on the continent, even way out in the boonies. If you get seriously off-road, sure, you might not be able to find 91, but as long as you are in a community with a population of 2,000 or more, I am pretty sure you will be able to buy 91.
I kind of suspect (this is speculation) that as automakers squeeze more and more horsepower out of smaller displacement engines - especially engines that are turbocharged - we are going to see that 91 octane fuel is a prerequisite for these engines. I mean, a 2.0 liter engine is only 122 cubic inches - that's tiny, absolutely squat-all - but the 2.0 liter TFSI engine in the Eos makes 200 PS, which is downright friggin amazing. As recently as the beginning of the 1990s, I don't think even the exotics (Ferrari, Lamborghini, etc.) were able to get 100 PS per liter of displacement. Look at my 6 liter engine: It only makes about 70 PS per liter, which is pretty wimpy in comparison to an Eos engine. Perhaps that is why I am allowed to run regular in it if I want.
My position is, I think, fairly neutral: Look at what the spec on the fuel cap is, and don't put in anything that has a lower knock resistance than what the spec on the fuel cap states.
Michael


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## EOSmage (Feb 9, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_My position is, I think, fairly neutral: Look at what the spec on the fuel cap is, and don't put in anything that has a lower knock resistance than what the spec on the fuel cap states.

Michael, with regards to VW, you've probably forgotten more than I'm likely to know.







So, I also highly respect your opinions (even when you state that it is speculation).
I agree 100% with the above statement, especially since they took the time to stick a warning label to the flap in the first place.
All I was saying with my post was that I doubt we'd be junkyarding our cars by using the lower grade fuels. I plan on following the advise of the sticker, the price difference isn't large enough to make me doubt the sense in it.
Question: Is there anyone in the forum that plans on using nothing but the low-grade fuel? It might be interesting to compare engine service/maintenance over a longer term with that of someone who uses nothing but the "good stuff". Anyone ready for a 5 year investigative investment? 



_Modified by EOSmage at 1:11 PM 3-23-2007_


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_
My position is, I think, fairly neutral: Look at what the spec on the fuel cap is, and don't put in anything that has a lower knock resistance than what the spec on the fuel cap states.
Michael


Hi Michael,
Excellent post, as usual.
For discussion sake I have to ask the question, which documentation takes precedence, the fuel door sticker, or the owners manual.
For the Eos I would suggest it is a combination of both documents, the owners manual refers to the fuel door sticker as a reference to the recommended fuel, but then uses an additional 3/4 of a page to identify optional fuel sources.
If it was as simple as "use what is on the fuel door sticker" you would think VW would have used about 1" of page room in the owners manual for a bold face heading and a one line comment: *Fuel Requirement:* refer to sticker on inside of fuel door.
I am going to pose the question to VWoC and we'll see what their "official" response is. Stay Tuned Eos fans!
Kevin


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*


_Quote, originally posted by *just4fun* »_...I have to ask the question, which documentation takes precedence, the fuel door sticker, or the owners manual.

Hi Kevin:
That is actually a thoughtful and very appropriate question.
The sticker on the fuel cap door is engine-specific. I know this from having done a bit of research on the subject in the Phaeton forum... there are about 20 different fuel specification stickers available for the Phaeton, depending on what engine is fitted and what market region the car is being shipped to.
The owner manual, on the other hand, is kind of generic in the way it discusses fuel requirements, excepting the very last booklet in the owner manual that actually documents technical specifications for the car (for example, liquid quantities, weights, measurements, and so forth). That very last section will probably contain a fuel specification for each of the different engines that are offered in the market region that the manual addresses. So, I would personally prioritize the information as follows:
*1)* Fuel cap sticker,
*2)* Specifications section of owner manual (list of engine specs, etc. at back of book)
*3)* General information section of owner manual.
But, that is just my own personal opinion.
Michael


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*

However, here is something that argues exactly the opposite of what I have been saying all along - it is an excerpt from a VW of America technical publication entitled "Eos Quick Specs Guide", published August 2006, that addresses fuel requirements for the BPY engine. The 3.2 liter engine is not discussed in this publication.
Be aware that although it is a US publication, the European measuring index for knock resistance has been used. So, subtract about 4 units from the number to approximate the USA measuring index (anti-knock rating) for fuel.
Michael


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_However, here is something that argues exactly the opposite of what I have been saying all along - 

You just have to love it when things are so straight forward, simple, and easy to understand.................






















Kevin


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## Pelican18TQA4 (Dec 13, 2000)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*

Why are there debates about using regular vs. premium?? If you don't want to put premium in your tank (like the owner's manual recommends and which the engine will thank you for), then go buy a car that recommends regular, period. Besides, the difference in cost is all but negligible when you factor in spending literally a couple dollars more per tank. If you can't afford that extra couple dollars then perhaps you can't really afford the car you bought.
I've had this argument with my Aunt plenty of times because she insists that her Passat 1.8T runs fine on regular. Is that why the ECU sets misfire codes almost every time she's been running regular for a couple tanks and it's NEVER occurred while running 91 min.?
Ok, stepping down from the soapbox


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (Pelican18TQA4)*

I don't think we are debating whether or not to follow the instructions, instead, we are trying to figure out how to _interpret _the instructions. At least, that's how I understand the thread to be - perhaps look the whole thread over again (read it from the top), and let me know what you think we have been discussing.
Michael


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## sydeos (Dec 30, 2006)

My experience with BMW mirrors Michael's and what I have read in other manufactures information.
In Australia we use the European RON system so all figures will reflect that. The BMW recommends 98RON but states that 95RON is acceptable and that 91RON can be used when nothing else is available.
This is saying that the engine will operate or run normally but that performance will be degraded below the optimum figures.
The manufacturer will usually quote the power and torque figures for the engine based on operating the engine on the recommended fuel grade. In my case 98RON, if you use a lower fuel grade then you will get a lower power and torque output from the engine.
However I noted the other day on the specifications for the Astra Twin Top that the power and torque figures were quoted on using 91RON and that higher figures were available using a higher grade of fuel. Just what they might be was not specified. I guess they believe from a marketing point of view they are better off specifying regular grade fuel usage instead of higher power outputs








But as Michael said the maximum performance for your engine will only come using the highest recommended grade for your engine. It will not deliver a higher output using a higher fuel grade that it was not designed to use. And if you use a lower grade you will get a lower level of performance from your engine. 
Like most things in life you never get something for nothing, it always costs something


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## PanEuropean (Nov 3, 2001)

*Re: (sydeos)*


_Quote, originally posted by *sydeos* »_But as Michael said the maximum performance for your engine will only come using the highest recommended grade for your engine. 

The issue that I am still not sure about is whether the nuance is 'you will only get *maximum *performance' if you use the recommended grade, or 'you will only get *optimum *performance' if you use the recommended grade.
In the case of my engine (the W12), the answer is very clear, I will only get *maximum *performance if I use the higher of the two grades. The engine will still perform well on the lower grade and no cautions are offered. Maybe I might be looking too closely at the wording, or perhaps trying to split hairs too finely, however, I wonder if for some engines, you get less than *optimum *performance with lower grades. In other words, do your exhaust emissions go up if you use lower grades, or would your overall fuel economy (dollars spent per mile driven) go down if you use lower grades?
That is the part that perplexes me.
Michael


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## flubber (Sep 12, 2005)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (EOSmage)*


_Quote, originally posted by *EOSmage* »_Question: Is there anyone in the forum that plans on using nothing but the low-grade fuel? It might be interesting to compare engine service/maintenance over a longer term with that of someone who uses nothing but the "good stuff". Anyone ready for a 5 year investigative investment?

Another interesting test--and a much quicker one to do







--would be to see if part of the reduced performance for lower octane gas is lower gas mileage.
91 octane costs 20 cents per gallon more than 87 here, so even 10% better mileage would mean 91 octane is cheaper to run than 87 when 87 is over $2/gal. Around here it's been a while since regular gas was that cheap.


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_I don't think we are debating whether or not to follow the instructions, instead, we are trying to figure out how to _interpret _the instructions. Michael

That is my ultimate intent, to clarify the information presented.
I will put premium in our car at all times, unless premium is unavailable for some reason.
To summarize:
1. The sticker on the fuel door indicates only one fuel grade min. (R+M)/2 91 (premium). there is no "range" of octanes noted. (this is on a Canadian spec Eos, I assume the US spec is the same)
2. The owners manual identifies various blended fuels that are acceptable for use in the Eos, and indicates they must be 87 AKI or higher (the manual references AKI instead of (R+M)/2). The owners manual also specifically indicates that engine damage may occur if you use fuels with octane ratings of _*less*_ than 87.
So what we are trying to clarify is: 
1. Does one source of information supercede the other, or do they compliment each other. 
2. If a lower grade fuel is used (either by choice or by necessity) is the ramification strictly performance based, or is there a risk of damage (engine, catalytic converter, etc.)
My interpretation is that the manual instructs the owner to refer to the fuel door sticker for information on the "recommended" octane rating for their engine. The manual then goes on to identify specific criteria for other fuels that are "acceptable" for use.
Before any definitve statement is made in response to Dave's original inquiry, we are just trying to determine for certain if the owners manual has the correct information, or if the 91 designation on the fuel door sticker means "use this fuel only, or risk damage to your car".
Kevin











_Modified by just4fun at 9:21 AM 3-24-2007_


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## PanEuropean (Nov 3, 2001)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*


_Quote, originally posted by *just4fun* »_we are just trying to determine for certain if the owners manual has the correct information, or if the 91 designation on the fuel door sticker means "use this fuel only, or risk damage to your car".

Though it might sound like I am contradicting what I wrote above, I doubt if any damage would arise as a result of using fuel with a lower anti-knock index that what is specified on the gas flap sticker, as long as the anti-knock index is above 87 on the North American scale. This is because the engine controller has the ability to adjust the engine timing, etc. to cope with fuels as low as 87, in response to messages that it gets from the knock sensors mounted on the engine block.
I do know that if you put less than 87 octane (North American scale) in a Volkswagen, the car gets really sick, and really pissed off at you. I recall driving through the Czech Republic a few years ago in my Swiss Golf (a MY 2000 car with a 1.6 engine in it), and filling up with the cheapest grade of fuel sold at a fairly large gas station. I don't recall exactly what the octane rating was, but I do recall it was way, way lower than anything I had ever seen before in Europe, and way lower than what the sticker on the gas cap specified. Anyway, about 5 miles down the road, the CEL (Check Engine Light) came on, the car started to cough and sputter, maximum speed fell to about 70 MPH, and I thought the car was going to die. I spent the rest of the afternoon - the rest of the trip to Dresden - stopping every 30 miles and filling up with the most expensive fuel I could buy (Super Plus) in an attempt to dilute the low-octane fuel I had put in.
That was an unforgettable experience.








Michael


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (PanEuropean)*

OK, I had a call back from VWoC Customer Care today and here is the "official" VW response regarding octane ratings for the 2.0T.
*Note: this is from VW of Canada, I am fairly confident US specs are the same, but read your owners manual, and contact VWoA if you require further clarification.*
My interpretation of the information contained in both the owners manual and on the fuel door sticker was correct according to VWoC.
91 Octane is the *recommended* fuel for optimum performance. Any fuel that meets the criteria specified in the owners manual and is 87 octane or higher is *acceptable* for use in the Eos 2.0T without concern of damage to the engine or other components.
So, unless the US owners manual contains different information, the answer to Dave's original inquiry is YES, it is safe to run 89 octane fuel in your Eos without concern of damage to the engine or other components. However, to acheive optimum performance, use the recommended minimum 91 octane grade fuel.
*Footnotes:*
1. I also inquired about any advantages to using fuel with octane ratings higher than 91. The response was that there was no definitive known advantage, however individuals may notice minimal improvements in performance and fuel economy.
2. The owners manual states that if you are using fuels blended with alcohol, ethanol, or MTBE and you experience any loss of fuel economy, or driveability and performance, to switch back to unleaded fuel.
3. All the information I have supplied above is from the Canadian owners manual, and represents responses from VW of Canada. We do not have the 3.2 V6 offered here, so if you have a 3.2, consult your owners manual and contact VW of America if you require further clarification.
Kevin









_Modified by just4fun at 1:43 PM 3-27-2007_


_Modified by just4fun at 1:49 PM 3-27-2007_


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## EOSmage (Feb 9, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

Excellent clarification Kevin. Thank you!


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (EOSmage)*

Since we are on the topic of fuels, here is an interesting news release that suggests ethanol blended fuels are no better than traditional unleaded fuel when it comes to greenhouse gas emissions.
There are no details on the study provided, so it isn't possible to know if the test vehicles were FFV's (Flexible Fuel Vehicle) specifically designed to optimize blended fuels.
http://www.cbc.ca/canada/manit....html
Kevin


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## _Rick_V_ (Jan 21, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (rebchief)*

This thread greatly amuses me-- it is a true indicator that this is an _enthusiasts_ site! Where else could we go to debate the finer points of fuel octane?! (God, I love this forum!)
My dealer told me specifically (without me asking, or prompting the conversation) that Volkswagens are flexible enough to handle regular gas without any problems.
That said, I've ignored this advice and have gone strictly with premium gas. Why? The manual suggests it, and (as pointed out by Micheal) it's cranking out 200hp from a tiny 2.0 liter engine! As a point of reference, I had a 1985 VW Scirocco in the that had a 1.8 liter engine that only put out a meager 90hp. We laugh at that today (especially if it was considered a sports car, like the Scirocco was!).
A previous car I owned recommended premium, but I tried regular a few times. I definitely noticed that it wasn't as peppy off the line (from stops). I switched back to premium.
But, it really boils down to this:
At a ballpark price of $2.75/gallon (I live in Chicago), it costs about $35 dollars to fill up from empty. It only costs about $2 dollars more to use premium. I can handle $2. For that little, it's not even worth sweating.
-Rick


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

This isn't related to Octane but I thought TB 01 07 55 *Gasoline Quality*, may be of interest to some forum members.
The TB deals with contaminated fuel or fuel that does not contain a high quality detergent additive. I wonder if this might help the sooty exhaust tips??
For more information on TOP TIER gasoline visit: http://www.toptiergas.com/index.html
*NOTE: this TB is informational only.*
















Kevin


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## Canadian Lurker (Nov 11, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

Yikes - I use an Esso station that is very close & convenient for probably 80% of my fill-ups for the past 8 yrs!! Since Esso isn't on the list, it looks like I'll have to switch - not really a big deal, but when you're into a repetitive habit it's tough to change.....








JJ


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (Canadian Lurker)*


_Quote, originally posted by *Canadian Lurker* »_Yikes - I use an Esso station that is very close & convenient for probably 80% of my fill-ups for the past 8 yrs!! Since Esso isn't on the list, it looks like I'll have to switch - not really a big deal, but when you're into a repetitive habit it's tough to change.....








JJ

Same here, we have both a Co-op and Shell station within a couple blocks from home, but I normally fuel up at Co-op because it is full service, and we have a membership, so we get a dividend cheque every year.
But I'm not going to risk fouling up the valves, it will be Shell from now on.
Kevin


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## ElkhornVDub (Jun 4, 2003)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*

Nice discussion. I'll add what I tell my customers:
It's fine to use 87, but for best performance use 91 or 93 (which is quite common in the midwest, or at least in Wisconsin).
Some bring it up right away - the majority of Americans I've run into, purchasing vehicles in Madison really don't want to spring for 91 or 93 octane. Why? Because they're cheap.
Those customers who haven't already made up their mind, I let them know with $3.00 gas, the premium they pay for 91/93 is well worth it, considering the increase in MPG I (as well as others) have experienced running premium, esp. in the 2.0T engine. I can understand when gas was $1.00, and premium was $1.20, the cost differential was much greater, resulting in people not wanting to use premium. 
It's sad that many of my customers still refuse to put premium in the vehicle, since they'll get that money back in increased MPG, thinking they're actually SAVING money. It's also sad to see customers burying $5,000 of negative equity into their next car, but many people do it. It's really up to them, and how they want to finance their life.
The sales trainer for VW that I often see runs all three grades in the rigs he gets from VW, just to see differences. His observations are close to what I've seen - the better the octane rating, the better the MPG - up to a point (93 octane, since I don't have racing fuel to test on a regular basis). 
I've used 87 in my '02 Passat 1.8T for most of it's life, and it actually came on a recommendation from a service tech after the car ran a bit rough in the cold Wisconsin winter. It did run better in the winter, and I wasn't all too concerned about MPG, with snowtires and such automatically reducing my MPG. In the summer, though, running premium results in better performance, as well as the better MPG.
Here's my take: Run premium when recommended. Try 87 in the winter, if you're getting rough idle/hard starts from the 2.0T, or even the 3.2 in the Eos.


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## solarflare (Mar 28, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (ElkhornVDub)*


_Quote, originally posted by *ElkhornVDub* »_ In the summer, though, running premium results in better performance, as well as the better MPG.


I've noticed an automatic 5 MPG gain from winter to summer. I believe this gain is due to temperature. I always wondered why my MPG, in any of my cars, was lower in the winter and I use to think it was because of the ethanol that was added to gasoline in my area during the winter months. It wasn't until I bought the Passat, which had the mpg computer, that I learned this difference was due to temperature. 
I can see how MPG can increase from running 87 octane to 91 octane but since the engine is optimized for 91 octane I don't see see how MPG can increase from 91 to 93 octane, unless your engine was not running efficiently to begin with








My commute is fairly consistent day to day, not sure if that's a good thing







, so I know what my MPG should be. I always use Sunoco 91 (not on that list







) octane so I'll try 93 octane for a couple fill ups to see if I get an MPG increase. I suspect there wont be.


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (just4fun)*


_Quote, originally posted by *just4fun* »_
Same here, we have both a Co-op and Shell station within a couple blocks from home, but I normally fuel up at Co-op because it is full service, and we have a membership, so we get a dividend cheque every year.
But I'm not going to risk fouling up the valves, it will be Shell from now on.
Kevin









*Note:*
I should point out that some gasoline retailers that are not on the list may well be selling fuel with high quality detergent additives that could be equivalent to Top Tier fuels.
The retailers on the list are the ones currently certified to be selling fuel that meets the specifications and testing requirements for Top Tier fuel. 
So if you are concerned, and don't want to invest the time to research your current supplier for fuel quality, choosing a retailer off the list is the simple way to ensure you are getting fuel with high quality cleaning properties.
Kevin


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## just4fun (Oct 29, 2006)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (solarflare)*


_Quote, originally posted by *solarflare* »_
I can see how MPG can increase from running 87 octane to 91 octane but since the engine is optimized for 91 octane I don't see see how MPG can increase from 91 to 93 octane, unless your engine was not running efficiently to begin with










I can't get fuel over 91 octane where I live (not easily at any rate) so I'm not able to experiment with various octane ratings. 
I have noticed an odd circumstance that seems to have a direct impact on the fuel economy of our Eos. My wife gets better fuel economy than I do....... now what could be the cause of that??















Kevin


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## SoCalMan (May 21, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (_Rick_V_)*


_Quote, originally posted by *_Rick_V_* »_
A previous car I owned recommended premium, but I tried regular a few times. I definitely noticed that it wasn't as peppy off the line (from stops). I switched back to premium.

-Rick

Our V6 Camry calls for premium (91) octane. Over the years my wife will occasionally put something in less than 91 to save a few bucks. When_ I_ drive the car, and the way _I _drive it, I notice the reduced power from the engine. 
As they say, timing is everything, and I rely on that power to get out of the way of another drivers incompetence. For me, its premium Shell, 76, or Chevron in our Eos and nothing else.


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## monocle (Jun 27, 2007)

*Re: IS it safe to use 89 Octane instead of 93 at my local US gas station?? (ElkhornVDub)*


_Quote, originally posted by *ElkhornVDub* »_Those customers who haven't already made up their mind, I let them know with $3.00 gas, the premium they pay for 91/93 is well worth it, considering the increase in MPG I (as well as others) have experienced running premium, esp. in the 2.0T engine. I can understand when gas was $1.00, and premium was $1.20, the cost differential was much greater, resulting in people not wanting to use premium.
My thoughts exactly. The $$ difference for a whole tank of gas seems minor... $40 vs $42


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## minnvw (Oct 16, 2006)

I run the middle grade , think its 91? cant tell the difference, hey we drive alot miles 30,000 a yr so it adds up for us, figure the oil company wont miss a few hundurd bucks? ha doug


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