Have an 03 Hemi and since gas has gone thru the roof, I just made the move to Regular Unleaded for the first time. Been on 93 since first drove it home and have been on 89 Mid but finally had to give in. Manual says Mid grade but prices are killing me. Talked to other on driving on 87 and say so far so good. Any long term Ill effects on the Hemi? I will switch back if ever the prices go down again. Any commemts would be appreciated, Thanks

 

Does it 'Ping' at all on the 87?

If not you will be fine.

 

Do a search, it's pretty much been determined that almost all who have had a cylinder go on them have admitted to running 87 octane gas over a steady period of time.

Not saying that EVERYONE who runs 87 octane gas will experience a major engine failure, but that most who do, are running low octane fuel.

Pre-detonation over a period of time is a very bad thing. Problem is, there could be pre-detonation going on and you don't realize it. Pinging and knocking are sure signs, but not always real detectable. Your choice, pay the $4-5 bucks more per fill-up or increase your risk of paying thousands on an engine rebuild later.

There is no reason or advantage to running 91+ octane on a stock tuned truck, but you should be running 89.

The only way I would consider running 87 octane fuel is if I used a tuner with a tune on it that retarded timing, like the 87 octane and fuel saver tunes on a Superchips...

 

what he siad ^^^

 

You're definitely going to experience problems over time with pre-detonation damage. It's 89 octane for a reason, and a reason I would never buy a used vehicle made to run on premium only..because you know people aren't doing it..Gas prices aren't that bad yet.

 

Yep, It's worth the whole $2.60 a tank full difference in price to keep the engine from destroying it self over time. I would never use 87 in mine.

 

These threads always make me laugh. Dodge tells you to use 89 for optimum performance but it is not mandatory. They tell you as well that 87 is perfectly fine to use. If you are not towing or constantly flooring it all the time 87 is perfectly fine.

 

Dodge will also tell you there are no known issues with dash materials, C-Clips, rear pinions, rack & pinions, etc.

Big sales advantage telling you "well you should really use 89 octane, but you can get by with 87".

Normally, any engine with a compression ratio over 9:1 will require a use of 89 octane fuel and when you hit about 10:1, you are talking nothing but premium. The Hemi has 9.6:1 ratio.

The reason they can get away with the "recommend 89, but 87 is ok" with a compression ratio this high is because of the EGR system. ('03s have no EGR and it's a big reason we see so many more people on these forums looking to replace blown '03s and not so much '04s, if they've been running 87 octane).

The primary purpose of the EGR is emissions and reducing the amount of NOX that is released into the environment, but a secondary benefit is that the gas dilutes the A/F mix slightly, which in turn lowers combustion temperatures and helps to prevent pre-ignition in the cylinders and thus lowers the octane requirement of the engine slightly.

HOWEVER, if you have a loss of EGR, which is VERY common either because the valve is dirty, non-functioning or ANY loss of vacuum is present then this cooling effect is completely lost and pre-ignition/pre-detonation WILL occur with 87 octane by virtue of this engines compression ratio. And remember, you usually won't generate an EGR code unless the unit has completely failed.

Again, I personally know people who have Hemi Rams and run nothing but 87 octane who have yet to have a major engine issue, BUT it significantly increases the risk of a major failure IMO. True, someone who uses nothing but 89 may drop a valve tomorrow with 50k on it while a guy who runs nothing but 87 may have 150k on his and it still runs, BUT the odds are WAY in favor of the engine running 89 having a long life...

 

Agreed, 0.10 cent different usually from one octane level to the next so 0.10 times 26 gallons is only 2.60 (89) a tank or 5.20 (93)

Surely you can to do and keep the engine happy.

 

Thanks Guys, all info was great. Going from 93 to 89 did make it run okay but lacked in get up and go. Now having 87 in the tank I sure have been taking it easy but I do pull a trailer so I just went back to 93 just to play it safe...
Thanks again..