Just got mine last week. Hemi of couse. Just wondeing what type of fuel to use. I want ot say 89, but I heard that 89 is total rip-off. What are you using?

 

I was running 89 and now I am trying 91. So far I get 300-303 with the 89, with 91 it is 330-333. So is it worth the cost= mileage ?? If the dang gas prices would level out then I would say yes. I also have a programmer I need to load and see the difference is with that.

 

I would check your owners manual and go by what their recommendations are. Everyone has an opinion but not everyone has the correct opinion.
kasjun

 

user manual says 87 to 89. That is why I'm asking around here. LOL!!! And a friend of mine say 89 is one third of 91 plus two third of 87.

 

yes they blend the different octanes to get the middle ones. I would not say 89 is a "total rip off", you are talking about $3 or $4 more per full tank. Try both and see what yields the best mileage for your truck and go with it.

 

I just use 87, I don't feel like I've noticed a different on the few tanks of 89 I've used. Also look at the official mpg thread, everyone gets about the same mileage using the different fuel. Depends on what you're doing also I'd assume.

 

The manual RECOMMENDS 89. I put enough trust into the designers of the engine to put in what they ask.

 

Was searching around and found that 89 is Recommended but 87 is acceptable. I'd say it's a owner call at that point.

Is there a big advantage of using 89 besides it being recommended?

 

It recommends 89 because if it has 87 the engine will ping and the PCM will have to retard your timing.

 

87 octane is within range for the knock sensor to retard timing, however, you do not get the claimed HP rating ( you cannot seat of the pants feel 10-15 HP). If you want to get the 390 claimed horsepower from your hemi, then use 89. Higher octane than this will not give you more power without a tune.

It is all in the owners manual, just run the recommened 89 octane, use the recommended 5w-20 oil and enjoy that new hemi !