Is it worth it to get a mixture of octane 100 and 91 gas once a month?

albert1028 · 07-21-2009, 07:48 PM

Hey All,

I have read through a lot of the gas threads and was wondering if treating my new baby to a tank of 93 octane (mixture of 100 and 91) is better for the car over the long run? or does it not matter.

By the way, I live in California where the gas is only 91 and select 76 have racing fuel octane 100 fuel.

What do you all do?

Thanks.

smmmurf · 07-21-2009, 08:45 PM

Run it all the time if you're going to run it. You don't do any favors to the car by running it on good gas "some" of the time. It's probably slightly worse for the car over the long run if you run 91 most of the time and 96 every once and a while--the car will adjust for the higher octane fuel and once you put CA 91 back in it will have to readjust back down... may ping a bit... probably not enough to damage it but it certainly isn't doing it any favors.

That said, 96 will make slightly more power... not enough to be useful (you already have 400+) but enough to show up on a dyno.

URBAN LEGEND · 07-21-2009, 09:25 PM

The cost won't be worth the few ponies.

07-21-2009, 07:48 PM	#1
albert1028 First Lieutenant 20 Rep 390 Posts Drives: 2009 E90 Space Gray M3 Join Date: May 2009 Location: Los Angeles iTrader: (0)	Is it worth it to get a mixture of octane 100 and 91 gas once a month? Hey All, I have read through a lot of the gas threads and was wondering if treating my new baby to a tank of 93 octane (mixture of 100 and 91) is better for the car over the long run? or does it not matter. By the way, I live in California where the gas is only 91 and select 76 have racing fuel octane 100 fuel. What do you all do? Thanks.
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07-21-2009, 08:45 PM	#2
smmmurf Colonel 309 Rep 2,189 Posts Drives: E92 M3 DCT 353k+ miles Join Date: Feb 2008 Location: Half Moon Bay, CA iTrader: (7)	Run it all the time if you're going to run it. You don't do any favors to the car by running it on good gas "some" of the time. It's probably slightly worse for the car over the long run if you run 91 most of the time and 96 every once and a while--the car will adjust for the higher octane fuel and once you put CA 91 back in it will have to readjust back down... may ping a bit... probably not enough to damage it but it certainly isn't doing it any favors. That said, 96 will make slightly more power... not enough to be useful (you already have 400+) but enough to show up on a dyno.
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07-21-2009, 09:25 PM	#3
URBAN LEGEND Rocky 412 Rep 3,085 Posts Drives: 16 M5, 18 ZL1 1LE, 18 M3 Join Date: Feb 2009 Location: Brenham TX iTrader: (0)	The cost won't be worth the few ponies. __________________ 22 Audi RS E-Tron GT 21 Model S Plaid
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