Hmmm...

I've got a 1996 Dodge 1500 V8 5.9L with a mopar Performance PCM and running 92 Octane no problems but looking at some of these post I might try backing down to the mid-grade and trying the 89 Octane grade and see if it holds good...

 

Anyone really oughta just run the highest grade, regardless of performance. From what I've been told, the higher octane burns hotter and cleaner. Plus, it usually will only be about a $2 or $3 difference per fill-up...at least around here. But most ppl, myself included, tend to run what's cheapest. I may at least go up to the 89.

 

I have put 89 in it now and agin to clean the motor out.

 

The highest they have up here in Maine is 91 and so that is what I use and going to get tuned for.

 

Here in the netherlands we use 95 octane, but sometimes when i drive to familie in germany i fill up in germany with the 91 octane, and i have to say, the engines runs more agressive when i use 91.

 

I use shell 93 octane with octane booster. Ive also been known to run a little Av Gas (100+). Ive been getting 10-13mpg. Half high way. On full high way no trailer i got 15. Thats checking myself not the computer. I know that sounds weird but im not complaing.

 

Premium Fuel only. 93 octane.

 

YES! So I am not the only freak out there then, lol.

 

haha nope..gota love it. smells good too.

 

Over there, you guys have a different octane measuring system. You have to take your rating multiplied by 0.95 to get the approximate equivalent U.S. rating. Your 95 octane is about 90-91 U.S. octane, and your 91 octane is close to 86-87 octane.

The engines (stock tuned) are designed for 87, so anything significantly higher (91+) will not benefit you at all unless you need it to reduce pinging (blown plenum gasket) or you acquire a programmer to get your engine tuned for that higher octane level.

Running higher octane without a programmer/performance tune will usually hurt performance, actually, as the computer is trying to burn your higher octane level gasoline with settings designed for 87. That is, of course, if you don't have engine issues that warrant higher octane to hide them, such as a blown plenum gasket.