What gas and why?

[rd02gt]

does any one run 87 on there mustang gt, or is that just a stupid thing to do , and will it change my acceleration if i use 91 vs 87or 89? thanks

 

[KaPPaBaLL]

mr. bayarea. Unless you're spark timing is advanced there is no reason for you to use anything higher than 87 octane gas. Rule of thumb: Use lowest octane gas possible without pinging or detonation.
If you do use 89, 91, etc (anything higher) you'll suffer lower performance.

 

[Bullitt_#1346]

Exactly, unless your car has been modded to take advantage of the higher octane fuel (read increased timing) you are just wasting your money, and the gas won't burn as well as the 87 octane it is designed to run on. If you are getting detonation, then move up to 89. That is all that higher octane fuel is for, preventing detonation.

 

[Go HoTO!]

Ditto, those guys are correct.

If you have an older car with lots of miles, you may need higher octane to reduce knock due to carbon build up. It is more slightly more common for older cars to require higher octane fuel.

 

[john_324]

As has been said, I think the best rule of thumb for an stock car is to use the lowest octane level that doesn't give you detonation.

I usually run 87, with an occasional tank of 89 (I occasionally get pinning at high, sustained speed when hitting the gas in 5th).

 

[Blue Mach]

I usually run 87, with an occasional tank of 89 (I occasionally get pinning at high, sustained speed when hitting the gas in 5th).

Same here about 90% of the time I run 87, sometimes I put 89 in.

 

[MustangJunkie]

Do what the manual says (run 87 octane). Why pay more than you have to, especially with gas prices where they are?

 

[Blue Mach]

Do what the manual says (run 87 octane). Why pay more than you have to, especially with gas prices where they are?

 

[john_324]

Speaking of the manual, I've always found it odd that it says that occasional detonation is normal, and you shouldn't worry about it (or something like that)...

What's up with that? I thought detonation is always bad. I don't know a lot about cars, but I'm fairly sure that detonation is always cause for alarm. Any expert opinions on this? Why would Ford say such a thing?

 

[MustangJunkie]

98BlackGT, did I say something wrong?

 

[john_324]

I think that's the smilie for "I agree with you", stupid...

(just kidding!)

 

[MustangJunkie]

I think that's the smilie for "I agree with you", stupid...

I didn't think I wrote anything that was entirely disagreeable.

Where are you in Washington? Are you in the city or in the subarbs? I grew up in Northern VA (Falls Church and McLean). I'm moving back there in a few weeks.

 

[Blue Mach]

98BlackGT, did I say something wrong?

No dude I was just agreeing with you

 

[MustangJunkie]

For a moment there I thought I was stupid.

Can't wait to drive my car home from work and then to dinner tonight! It's a sickness...