LAKERLVR

Which octane should I use to get the best performance (regardless of price) for my 2005 Mustang GT. I ask because I know the manuel says it can take downwards of 87 Reg Octane but will running 90+ give me any performance benefits or is it more dangerous and potentially damaging to the car. Thanks

delurker

Use the lowest octane at which you don't get pinging. Cheapest and best performance. Using higher octane won't hurt the car, but it is a waste of money. I have mine tuned for 91, so that's what I use; if she were bone stock, I'd use 87.

MikeHawke

there are no benefits whatsoever to be had by putting higher octane fuel in your than is necessary.

All octane does is make the fuel more resistant to ignition, which is good for a car with advanced timing or higher compression due to forced induction. But it offers no gains for a car that is tuned to run on "regular" unleaded gasoline. In fact, the really high octane fuels like 94 may actually be a little bit detrimental to your car becaue some of the fuel may not be burned.

In other words, save your money. A stock GT is tuned to run on 87 and that's all I put in mine. If you get a tuner or a custom tune, you should run whatever fuel is recommended because these engines DO NOT like detonation.

6xStang

My LS6 has two timing maps; the high output timing map set for 93 octane. When preignition is detected it is supposed to kick down to a timing map which retards timing to presumably avoid the preignition. There is a noticeable power loss when that happens, though.

Does the OBDII/knock sensor on the Ford 4.6 work the same way?

dhg

Daniel60

I use the 87 octane with the brenspeed tune/CL Air Induction kit. I really can't tell the difference between the high performance tune that requires the high octane or the regular tune that uses the 87 octane.