Em_DynamicTurbo

What type gas put 1991 Mustang LX 5.0? I've been putting 93 octane for a few months now. but i wanted to know if i can put 89 or 87

motorman524

Based on your sig, I'd think you know the answer to your question.

Em_DynamicTurbo

Well, unfortunatley I don't know the answer. And I was told to put 93. But I wasnt sure, hence the Post.

newpony

GasStations ive ben to only sell 91. i belive is depends on you tuning ,yet it clearly states on the fuel door)unleaded)i'm guessing ,not sure i always use 91, whats recommended.

you may need some 110 still depends on tuning and motor

The_Dude

My stock '91 5.0 LX seems to run fine on regular.

craig71springsport

Try alcohol.

dwb91lx

My 91 shop manual (I think) & owners manual says 87 octane regular unleaded...My recent Bama Chip purchase may get 92 octane next fill up to try out the 91R tune.

mustangGT86_05

You can't just go and buy leaded fuel anymore, I think the only way you can get it is to buy it as an additive. They only say unleaded because lead wrecks catalytic convertors yet I see all the time people for some unknown reason have the conception that high octaine fuel is leaded. And 110?! That is extreme, if he required 110 I doubt his car would be street legal.

Consider this, the ho 5.0 is a high compression engine, so that alone tells me put high grade in mine. Octaine is the resistance to detonation, if you predetonate most electronically controlled engines retard timing to compensate, this will kill your performance.

There seem to be many misconceptions about gas, but a higher performing engine will need something more than just 87.

mjr46

put diesel fuel in it.........

majohns

i know with with my last mustang i had an sct tuner and on a 93 octane tune you have to run 93 or higher because it would start pinging. this was in a 4.6, i would assume it would be the same on the 5.0 though. i personally run 93 in my cobra stock engine. but i went from 9MPG in my truck to 18MPG in my car so the cost doesn't bother me to much. all in all, you can safely run 87 on a stock tune but if you have a 93 tune run 93 or higher on that tune. you can also mix about 5 gallons of race fuel with your 93 and make it even better plus it smells awesome.