I have an 03 4x4 hemi and I run the 89 as recommended. Runs great. The 89 and 91(here in CA) require a higher temp for combustion, therefore great for the good ole American muscle. 87 is previously known to cause the knock. Here's what's funny. I also ride a CBR954RR sportbike and I run 87 in it though recommended 91. I run way more powerful and get better mileage off the 87. Go figure.

 

Yeah, but then your computer is setting the timing for 87, to make sure it doesnt detonate too early or late. 87 just isint as clean as 89, and it doesnt burn as effeciently.

 

My owners manuale recomends 89 octane unless the government is trying to rape me at around 3 dollars a gallon. If this is the case the manual states I can run 87 octane for as long as needed to easily make my mortgage payments. Oh yeah, I switched to synthetic oil at 55 K miles w/ no problem.

 

I don't race it and when I know I'll be towing, I'm sure to use 89. Anybody that has been around here a while knows that I baby my truck (for the most part). She does what I ask of her and I do what she expects of me:
1. Not beat on her
2. Keep up with her low maintenance (more than I can say about some women)
3. Keep her clean

If I do that and keep 'Trinity' happy, I know that she'll keep me happy with years of trouble free service.

 

LOL heh, that's funny.

 

I fill her up twice on 89, once on 93-94, then back to twice at 89 etc. She seems to like it.

 

Been runnin' ours on premium, I would highly recomend you do what the manual says 'cause they're the ones who built it. If it's been run on regular, I don't think you have to go to extreme like syphon the gas out, but I'd stick with premium to be on the safe side.

-BigRig

 

When I'm not driving my new 06 PT Convertible I always use 87 oct. in my Hemi except when I tow my boat. Then I put in 89. That doesn't mean I fill it up completely with 89 I just put 89 in on top of the 87.

 

87 will work 89 recommended, I have run 91 and have not felt a difference so I save an extra 10 cents and use 89.

 

I mostly run 87 since my truck runs no diferent on 87 than it does on 89. If towing during the heat of the summer, I'll usually fill with 89. My manual specifically says, anything over 89 is not recommended and can actually hurt performance.