I guess is what ever you want to put in it , the manufacturer ask for 89. but many people swears by 87 and others by 92 or 93 so i guess the the pumps are open for anything you desire . personally i use 93 from the moment i got it people will say i am wasting money so don't care i am the one working for it . so just do what ever u think is best for you.
I own two hemi's. 2003 1500 qcab 4x4 and an 04 Durango Limited. Both run exceptionally well on 87 octane. I did put K&N filters on but thats the only modification. The 04 has 37,000k and the mileage on highway is extraordinary. No Lie I am getting consistant 20-21.5 mpg on highway and when driving cautious, I get 16 around town. The truck had a 3:55 rear end axle and I did not know, I ordered it with 3:92's. When I found out, I went to the dealer and demanded the 3:92 gears. They are doing that next week. 03 truck has 20,000 miles on it. I pull a cougar 245 5th wheel with 87 octane as well.
I have my '95 5.0 timing advanced to the limit so I have to run 93 octane. Exxon's ALWAYS pings, so I generally use Chevron or Shell. Even Walmarts gas doesn't ping like Exxon. Dont know what the deal is with them.
i ONLY use BP/Amoco 89 octane....great quality stuff...i know there are several opinions concerning gas, etc....but I've read that the BP/Amoco is one of the best quite a few times in different studies, etc...
Brand usually doesn't matter too much. All basic 87 Octane gas and 93 Octane gas are virtually identical when manufactured. Notice I didn't say 89 Octane gas, well, that's because 89 Octane gas is not manufactured, it is mixed. Newer (within the past 10-15 years) gas stations have two holding tanks, one for 93 and one for 87. When you pump 89, it pulls a mix of 65% 87 and 35% 93 for a octane rating of 89. Older stations have 3 tanks and the fuel distrubitor hauls the mix seperately. The only difference a brand makes is when they add detergents and additives to their gas. Basic 87 Octane gas usually doesn't have any additives hence making most 87 octane gas virtually identical across the brand spectrum. So if you're buying 87, your best bet is to buy at a gas station that does a good amount of business, therefore keeping the fuel supply fresh. The fresher the gas, the less problems you will see like pinging and sputtering.
Higher octane gas will result in better performance and fuel mileage. The difference, however, is nominal. When I was tuning my old Mitsubishi Evolution I remember Dyno graphs that showed maybe a 5HP improvement with higher octane gas - not usually noticeable by the seat of the pants dyno that most of us use.
Personally, I'd recommend using 89 because you're more likely to get some additives that are added into the 93 octane gas. However, it really is a crap shoot considering it is usually 10 cents more a gallon which translates to 2-3 dollars a tank for most of us. Is 2-3 dollars with a few gas additives and a little better performance and fuel mileage? I think so.
As for brand, well, you could argue all day about who uses the best additives. I guess that boils down to whichever brand's advertising you like the most.