I have spoken to a few local folks who have the 5.7 Hemi engine and they all recommend putting in the highest grade fuel available. Here in Ca. it's 91 octane only.

I looked though the owners manual on my 2003 Dodge truck and did not any mention of using 91+ fuel.

Anyone got any opinions on if 91 will do better for overall performance than 87 will or is this just a personal preferance??

Thanks
Stu

I run 93 in mine but I also run a tune and anything less pings like hell.

before I hit my magnum w/ the programer I ran 87 w/ no problems, but I hit it w/ a 93 tune so I have to use 93. I guess I could always swap it back to the 87 until I go to the track.....

you should double check your manual because I had a 2003 ram 2500 with the hemi and it did recommend 91 or above for fuel. I did some research back then and found that very few engines these days do need high octane fuel. The hemi falls into that category because it has high compression. I always ran mine on on 91 or above and never had any engine issues.........rust, however was a different story.

Stu, we leased an 05 Durango with a 5.7, we always used regular, always ran fine, no problems for 48k miles

I looked in my 05 owners manual and it said "recomend 89" , I just looked in my 07's and it says the same thing...have always ran 87 with no problems ever...if towing I'll use 91

87 oct. for me I have 90k on my 2004.
If I tow I use 89...never pings. never

You are probably fine, but I believe they do better with a little more octane. I did have an 04 hemi truck and I always ran 87, but if I could go back in time I would probably have run atleast 89.

I only say that because of what I have noticed with my 2010 challenger. I run 93 now because of the tune, but I ran both 87 and 89 with the factory tune and data logging showed me quite a bit of knock on hard runs. I will also say that I could not hear it so just basing it off of sound doesn't mean it isn't happening or trying to happen.

just my .02

They recommend 89 but we run 87 in both the 04 Hemi Ram and the 05 300C. We don't beat on them and run the stock tunes. I've never heard either knock, I've also never raced either one.

I have 94,000 on a 2007 and I have run 87 octane almost exclusively. I have tried 89 and 91, but I couldnt tell any difference.

Stu, check the OM again as its in there some where. On mine, 89 as recommended in OM, 91 with diablo tune(W/CAI&180* T-stat),D

Good info!! Thanks guys!!

I run 89 in my 2010 Hemi Ram, no issues!

The California 87 swill here Stu, for Rene's magnum.... I've run 89 and I can't tell a diff

Mid grade as recommended in the 06 Daytona
Premium (if you can call it that out here) 91 in the 6 speed.

I have a 09 Charger, owners manual says 87 is recommended, 89 is ok but do not run higher than 89

I have an 07 300C and an 07 Charger R/T, both have the 5.7L Hemi. The manual states 89 octane. When 89 isn't available use 87, and it says premium gas is NOT recomended.