today i accidentally filled up about half a gallon with 87 regular instead of 91. my other car takes 87 and i just had a brainfart for a few seconds before i realized what i was doing. i stopped and filled the rest of the tank with 91.

will half a gallon of 87 mixed with 13.5 gallons of 91 do any harm to the engine? void my warranty?

 

a half a gallon, you worry to much..

 

that wont dilute the 91 by that much.. if ur super worried just dont dog the car for this tank of gas and run it low, but honestly that small percentage fo 87 wont dilute the 13 gals of 91 by too much, so not too much of a concern.

 

^ umm the NOS octane booster is the best. Sorry to say it but, it bumps by octane numbers not points. 10 points to an octane number. But I think he should be fine with only half a gallon in. Just when its halfway empty fill up again to kinda flush it out better, and arent you supposed to use 93?

 

cali only has 91pisstane

 

Yea I put 92 in my car last night. I didnt realize they only had 92 and not 93. No big deal

 

exactly..
a half gallon of 87 isnt going to hurt anything if the rest of the tank is filled with 91...
but if you're that worried about it, go drive around for 10-15 mins burn off some gas and then go top it off with 91.

 

The Evo is supposed to run with 93 octane per . I understand that Cali doesn't offer 93 octane (which sucks nuts, btw) so running a touch lower in octane than what you have been shouldn't be a problem. I personally would be dumping in octane boost on every tank, but I know that can get costly.

 

you'll be fine without putting anything in. but, you could put in some GOOD octane boost....the NOS stuff is ok the 104+ (black bottle) is a lil better thats what i use......then you'll probally be better than just strait 91...its probally closer to 91.7

 

Living in NJ we are not suppose to pump our own gas. This dumb *** start filling my tank with regular (87). After a $1.50 I notice and jump out of the car lol. I was like, I need premium man. Luckily (imo) 93 is much more common in NJ than 91 and I filled the rest of my tank with it, no problems.

Not to hijack your tread, but does anyone know if running 93 on a 91 tune does anything, good or bad, for the car?

 

well it cant be good lol i dunno about bad but itll prolly rob some power?

 

I accidently filled half tank of 87 once. No biggie - there was no problem. If you do it couple times you can say bye-bye to injectors, but half a gallon is not a problem.

 

Cali only has 91? Are you serious?!

 

.5 gallons, and 13.5 of 91, dude you have nothing to worry bout

 

just do the math, it's not that hard.

(.5gal*87 + 11.5gal*91)/12gal = 90.833 avg octane. not a big difference to 91.