Most of the newer engines are "factory tuned" to perform with specific octane gasolines. Although it's perfectly fine to use a higher octane fuel than is called for, in many instances you will not get any benefit from it. You'll have to experiment with it. If you run smoother or have a clear mpg benefit with the higher octane, stay with it. On the other hand, NEVER use a gasoline with a lower octane rating than is called for. As the 'dog said, detonation (knocking & pinging) is very bad for the engine...

 

I agree, but is there anyone that know what octane the Dodge RAM have for "factory tune"?

 

Well, I believe the Hemi should be 89 and the others should be 87. At least thats what I remember reading in the manual.

 

the reason it did better with 93 than with 87 is because the hemi is designed for 89. with 87, it was probably retarding timing when you floored it to suppress detonation. The benefits you saw with the 93 are probably there with the 89 as well. Once the octane is high enough to suppress knock, you've gotten all the benefit you can out of that fuel, going higher wont' do a thing for you. except in cases like semigod where the 89 has more ethanol in it.

like Hammer said, running lower octane than recommended used to kill engines. many modern engines (including the ones on the ram) have knock sensors. running lower octane causes the engine to knock/detonate/ping and the ocmputer retards the timing to stop it. you won't damage the engine, but you do end up losing power/economy. .

running a higher octane tahn recommended does not benefit you unless you are deliberately advancing timing (powerwire, superchips, diablo...) past what the engine would normally do.

also, the only time you will really get detonation is startup, high load low speed (bogging), or when you're flooring it. avoid thsoe situations, and 87 will work just as well for you as 89.

 

so when I have to use 95 oct. (that is the lovest oct I can get here.)
I am not getting all the benefits I can out off this gas?

I should be able to adjust the timing on my 2002 5.9 ram!
Is there any way to do that?

I have the superchis and run at the time the miage XS program cause this seems to give me more mileage than the 91 oct program.

 

did you mean 85 octane? the superchips will advance timing in certain settings, not sure what setting does and how aggressively, but the performance tune will do it.

DO NOT run 85 octane with performance tune. your engine will hate you for telling it to advance timing and then giving it fuel that knocks when you advance.

 

no I have only 95 oct... (I can also get 98 oct) This is the only choice we have here in Norway!
95 oct is the lowest quality I can get...
That is the reason I want to move my timing! To have full advantage from the fuel capacity!