No, 87 OK but 89 recommended.

 

I run 89 and I get about 14 MPG. when I first got my Ram I only used 87, until I read that it works best with 89. It may be all in my head but it seems to run a little stronger with the 89.

 

I've run 87 and 89 and can't tell the difference. The computer doesn't adjust the timing for different fuel. It retards it IF the knock sensors sense engine knock, and is very slow in doing so. You will hear the knock long before the timing is retarded.

 

Unleaded

 

I have an 04 Quad Cab 4x4 Hemi. I changed the exhaust to duals ,both pipes are 2.5 inches. I have a K/n filter and I pull a 21 ft boat with dual axles ,the whole rig weigh's around 5,000 lbs. I use 87 octane all the time. I bought the truck new and when I try the higher octane fuels my mileage drops. This past spring I had the truck dino tested and at the engine the motor was rated at 390 HP.

 

Silver Eagle, I would need to see the sheet to believe that one. How did you get the HP at the motor? You pulled the motor out of your truck?

I am going to call bull on that one. 390 is huge.

 

Agreed, post the dyno sheet.

 

Maybe they got a rear wheel reading and estimated the fly wheel reading???

 

I use 89... I have use 87 and the truck seemed to loose power. I know that in many ways the Hemi is similar to the GM LSx motors (hell the valve springs are interchangeable), and I have seen Z28's pick up 45 HP going from 87 to 91. I figure 10c a gallon equates to 5% of the cost of gass at most... you can gain 5% fuel mileage by not acceerating hard a couple times... I am a risk taker but this is one bet I choose to hedge.

 

let me start it this way. I'm a dodge person and more and likely always be. Had a dodge van and always ran silver (89). When I took it to dealer for the recommended service, fuel system cleaning ,he told me it was the cleanest system he has ever seen. So now to the recommended octane, it is a pity to put anything less than 89 octane into a HEMI , unless I'm in a state that only has 87. The cost of what might go wrong in the long run is not the cost of putting in 87, ... So follow recommended in service manufacturer Manuel, your truck will love it and give you many years of clean burning MPG.