# Which gas for a 2012 Eos?



## zchristian1 (Jul 28, 2009)

I had 2 different salesmen tell me different things regarding gas. One said I had to use Premium and the other said it was optional and it's okay to use the medium grade, Plus, or just Regular.

What's the real deal? Is it okay to alternate the quality of gas each fill up?

Thanks!


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## sapphirexae (Apr 25, 2010)

I use only 91. VW recommends it, so that's what I do. I'm sure regular would be fine but nothing but the best for mine.


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## astromutt (Feb 17, 2011)

I'd love to put the best in, but I'm only getting about 250 miles per tank and at that MPG, mine is doing OK with the mid-grade. No performance issues - just lower prices at the pump. Of course, I'd reconsider if my MPG went up significantly for using the top stuff...


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## BsickPassat (May 10, 2010)

zchristian1 said:


> I had 2 different salesmen tell me different things regarding gas. One said I had to use Premium and the other said it was optional and it's okay to use the medium grade, Plus, or just Regular.
> 
> What's the real deal? Is it okay to alternate the quality of gas each fill up?
> 
> Thanks!


Go look at the fuel filler door... it has a sticker that tells you


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## sapphirexae (Apr 25, 2010)

Odd, I average 30-33 hwy.


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## gtisponge (Mar 16, 2006)

The higher the octane the longer the fuel burns in the cylinder witch gives you more power


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## dasdub89 (May 3, 2010)

gtisponge said:


> The higher the octane the longer the fuel burns in the cylinder witch gives you more power


 
more power does not necessarily mean better gas mileage. in all honesty more power = less gas mileage. thats why 500+ hp cars get like....10 miles to the gallon


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## DavidPaul (Nov 28, 2009)

dasdub89 said:


> more power does not necessarily mean better gas mileage. in all honesty more power = less gas mileage. thats why 500+ hp cars get like....10 miles to the gallon


 Your analogy is quite incorrect. 

Extreme horsepower engines, being naturally aspirated depend on the size of the pistons and then forced aspiration is added for more HP. That is why they get poor mileage. 

If our vehicles had a larger or a double turbo or super charging for aspiration, the mileage would drop considerably when we get our foot into it. 

A finely tuned engine VS one that is identical but not tuned so well, will return more horse power and more MPG. 

Years of testing has and is proving this. 

You are not a mechanic, are you?


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## RatBustard (Jun 15, 2007)

not necessarily true. 

the rate at which the fuel burns relates to the compression ratio of the engine. 110 octane in some cars will make less power because of their lower compression and longer burn, thus reducing power. you need a compression ratio of ~12:1 to really feel the power of a high octane fuel - for most applications. 

as far as your eos, you can put regular in no problem. vw _recommends_ premium, but the engine will pull timing if you use regular. you won't get the performance or mileage from 87, like you would expect from 93, however. and really, at the pump, that equates to roughly three dollars more per 14 gallon fill up, assuming 91/93 is $0.20 more than 87. 

you'd probably spend more filling up with 87 over time because of the frequency you'd be filling your tank, as opposed to just biting the bullet and filling up with premium. 

am i a mechanic? no. have i designed an engine? yes - well, it was a carbureted engine, but nonetheless.


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## BostonB6 (Nov 16, 2005)

Regular gas: ECU retards timing to prevent knock = less power. 
VW lowered recommendation because people do not like to buy a car that requires premium.

/thread


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## GTINC (Jan 28, 2005)

sapphirexae said:


> I use only 91. VW recommends it, so that's what I do. I'm sure regular would be fine but nothing but the best for mine.


91 RON is the same as 87 AKI.

Use what the label on the fill door says, but be sure to read which rating system is used.

All VW petrol engines have knock sensors which allow the use of any commercially available grade safety.


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