# Gasoline 85, 87 or 97 ???



## Mitch82 (Oct 15, 2018)

I own the 2018 Atlas SEL-P V6 4 Motion.

In the owner manual, they are saying that we can use regular gasoline 87 or 91.

When I open the lid for filling the gas, the sticker there shows that we can put only Regualr :
- min. 87 AKI (R+M) // 2
- or 91 RON


The 85 is obviously less expensive.

I also want my Atlas to last long, I am not leasing it.


What is really the difference between 85 and 87, and why the 85 can't be used ?


I was using the 85 for the first 2 or 3 times I filled my tank. Never had issues, weird noises, etc...

Is it safe to use 85 or do I have to get stuck with the 87 ?



Also, I am living in Colorado, and I heard once people telling me that here it was better using the 85 due to the elevation. Not sure if this is right. No knowledge regarding this.


Thanks for your help.



PS
I tried the search function, but I either didn't use the correct keywords or never find an answer to my question. Even in Google.


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## AudiVW guy (Feb 7, 2006)

i use 87 as that is the cheapest gas we can find here .. 
not to mention we pay close to $1.10 per liter.. so every drop counts. 
I tried 87 89 and 91 - none of it made a difference - the Altas barely reaches 525 KMs a tank.. so why bother use the cheapest ..


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## KarstGeo (Jan 19, 2018)

Your Atlas is made to run on 87 octane "regular" fuel. 91 RON = 87 octane in other countries...this is not the same as 91 octane as we use it here in the U.S. At altitude, you have 85 octane out west which for you will be equivalent to 87 octane fuel down here at sea level.


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## BsickPassat (May 10, 2010)

KarstGeo said:


> Your Atlas is made to run on 87 octane "regular" fuel. 91 RON = 87 octane in other countries...this is not the same as 91 octane as we use it here in the U.S. At altitude, you have 85 octane out west which for you will be equivalent to 87 octane fuel down here at sea level.


OP is in Colorado. In the higher elevations, which technically reduces the octane requirement, 85 AKI is equivalent to 87 AKI for us flat landers.

87 AKI is equivalent to 89 AKI

97 AKI? Pretty sure that's a typo. On my drive through CO, the highest I've seen is 91 AKI.

....so, if you stay in the mountains of Colorado, 85 AKI is fine, until you go down by sea level, where then 85 AKI is not recommended, nor sold.

You noticed, I wrote AKI, not octane, since the number on the pump says AKI, which is Anti-knock index, which is an average of Motor Octane Number (MON, under load) & Research Octane Number (RON, no load)


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## GTINC (Jan 28, 2005)

Mitch82 said:


> I own the 2018 Atlas SEL-P V6 4 Motion.
> 
> In the owner manual, they are saying that we can use regular gasoline 87 or 91.
> 
> ...


All VW engines, including the engines for the Atlas, can be safely operated on any commercial available petro (other than E85). The ECU just makes a timing adjustment.


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## steveg241 (Oct 9, 2018)

BsickPassat said:


> OP is in Colorado. In the higher elevations, which technically reduces the octane requirement, 85 AKI is equivalent to 87 AKI for us flat landers.


That is certainly true when cars had carburetors but with today's modern computer controlled vehicles it is best to use the minimum octane that the manufacturer specifies. According to the EPA:

What is 85 octane, and is it safe to use in my vehicle?

The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower—because it was cheaper and because most carbureted engines tolerated it fairly well. This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine, you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available.

Full link:EPA: Selecting the Right Octane


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## GTINC (Jan 28, 2005)

steveg241 said:


> That is certainly true when cars had carburetors but with today's modern computer controlled vehicles it is best to use the minimum octane that the manufacturer specifies. According to the EPA:
> 
> What is 85 octane, and is it safe to use in my vehicle?.....


As the ECU adjusts timing based on fuel, all grades are safe. The higher the octane, the more power/torque.


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## aleksl (Oct 16, 2002)

steveg241 said:


> That is certainly true when cars had carburetors but with today's modern computer controlled vehicles it is best to use the minimum octane that the manufacturer specifies. According to the EPA:
> 
> What is 85 octane, and is it safe to use in my vehicle?
> 
> ...


But at high altitudes there is less oxygen and pressure, so compression ratio is reduced within the engine. If that engine doesn't have a turbo or a supercharger to overcome the loss of pressure it will make less power no matter what. This is why NA cars are much slower at altitude than cars at sea level. It will be less prone to pre-detonation. This is why his Atlas runs fine on 85 octane.

OP what is your altitude you're at?


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## Hfqkhal (Oct 14, 2018)

aleksl said:


> But at high altitudes there is less oxygen and pressure, so compression ratio is reduced within the engine. If that engine doesn't have a turbo or a supercharger to overcome the loss of pressure it will make less power no matter what. This is why NA cars are much slower at altitude than cars at sea level. It will be less prone to pre-detonation. This is why his Atlas runs fine on 85 octane.
> 
> OP what is your altitude you're at?


I read the posts here and read all over. The one thing I suggest is that if one wants to use the lower than 85 is to get it in writing form the dealership or else if anything goes wrong then the owner is responsible for the costs. Honestly it is not worth the $100 annual savings between the two and just go with the recommended 87. In my Murano, it said recommended premium fuel and the dealer gave it to me in writing that the use of 87 is fine and does not trigger a warrantee issue. The only difference was to get 267 HP on prem. vs 260 hp on regular. My understanding is that it is about the same gain with the Atlas. Above all the formulation of 85 vs 87 is deferent so one needs to be very careful. For me what I do is 3 fill ups with 87 then 1 with premium with tank never going below a quarter.


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## KarstGeo (Jan 19, 2018)

I stand corrected...don't use 85 octane in your modern car when the mfr says 87...even at a mile high.

https://fueleconomy.gov/feg/octane.shtml

And yes, I use the term "octane" in place of "AKI" b/c it's how most people know it.


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