'07 Corolla, 10:1 Comp...89 Octane?

elite engineer

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I have a 2007 corolla..my compression ratio is 10:1..should I be using 89 octane instead of 87. When I use 87 oct, my car exhaust puts out a sulfur smell..




04 Corolla CE 5spd
I also dislike the exhaust smell and reduced performance and efficiency on 87 pump octane (91 RON) with 10% ethanol. I use 91 pump octane (95 RON) which is locally available ethanol free.




I know Karate, Kung Fu, and 47 other dangerous wor
87 octane is the minimum that you need to run on this car - with the better fuel and ignition control they have now - even 14:1 (Mazda's SKYACTIV-G) on regular pump gas is completely possible. That old school thinking of 10:1 as being high compression is no longer the case. Just pump in whatever seems to give you the best MPG to cost.

Dom has a very valid point - pretty much all the regular gas you can find and many of the premiums have some percentage of ethanol mixed in. Generally 10% (E10 gas), some places in the midwest have E85 (85% ethanol). Though ethanol does burn clean, it is fairly corrosive to fuel system parts at higher concentrations, and you get less energy per unit volume - compared to gasoline. Sure it has a higher effective octane rating, but that doesn't offset the lower energy potential of the fuel.

I personally like to run purse gasoline, if I can find it. Atleast 10-15% more MPG, emissions are just marginally higher, nothing compared to those older cars that don't fall under emissions checking. For me, I actually spend less money by using premium fuel over the OEM recommended regular. Even at the higher cost on the initial fill-up, I recoup that cost by able to drive further on that same volume of fuel. Each car is different - some have a markedly difference in MPG and performance with different grades of gas, some do not. On my 2009 RAV4 - makes almost no difference what I use to fill up, runs about the same. On my 2002 Corolla - I can easily see a definite 10-15% increase in MPG, just by running a higher octane fuel.


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