So I was checking out my "Drive Dodge" app for the D3 while I was on layover in Seattle yesterday and found that they "recommend" 89 for the 5.7. 87 is sufficient but they do recommend 89. Thought it was interesting. Personally I'm going with 92 because I have the 91 tune and Costco only sells 87 and 92 up here. 92 CMR will be coming soon.

 

I noticed on stock so far, 87 was about 15.5 mpg. 89 got me 17 and so far no difference between the 89 and 93. Pretty much driving the same route, same speeds so far. I expect it to decrease when I get my HT as the pedal will be on the floor more often.

 

tried 87 and was ok...
I run 89 and can actually see and feel the difference. no ping on hill acceleration, and mpg is better... just turned 7k and gunna stay with 89

 

Yeah I noticed this too, been using 87. Any difference in the way the D runs with 89 besides 1.5 Mpg increase?

 

I am sticking with 89 or higher. The D runs better and gets better mileage for sure
STEVE

 

I've been using 87 since I drove it home from the dealer. Definitely going to use 89 next tank and see what a difference it makes.

 

I noticed it took a few tankfuls to see a difference. Must be the computer learning the new parameters and adjusting.
STEVE

 

I am going to try 89 too, as if 70 bucks a fill up wasn't enough..........lol

 

In case some of you guys don't exactly know what hydrocarbon.. Er I.e. " octane" does or is. This article is one of the best out there. Came across it some years ago and was just updated with more e85 info.

http://www.carbibles.com/fuel_engine_bible_pg3.html


Use at least the recommended octane if you want all of your advertised HP in all driving conditions unless you have been re- tuned for max power with 87.