85?! jesus why would you put that in there?

 

they had E85 down here for a while.....its designed for flexfuel vehicles, from what i understand. it is really really cheap, but no thanks...thats asking for trouble. since fuel has gone down, ive been running premium as well, for the tuner sake, and peace of mind.

 

to be honest, i didn't even look at the octane rating until i was halfway through the second fill up. i didn't think they could sell anything less than 87, never ever saw it less than 89 oct. in Idaho. i guess from now on i'll be paying for "premium" even though i can get that as regular in other states

 

E85 is not the same as 85 octane gasoline. E85 is 85% Ethanol, and 15% gasoline. 85 octane gasoline is a rating, and is usually all gasoline, or up to 10% ethanol. You CANNOT use E85 or gasoline containing methanol in your truck unless it is specifically made for that (you will have a yellow gas cap and it will typically say "flex fuel." Hemi's can't take E85. Some 4.7L engines can, but not all.

 

This is a VERY interesting thread and it leads well, I believe, into a question I now have.

I have generally ran 89 octane, Chevron (E10) exclusively, but once in a while straight 87 Chevron. I see a performance difference in going up in octane rating.

Now I have a ProComp PowerPro tuner; comparable to, and made by, Hypertech. I am currently running the 87 Tune using 89 Octane. After reading through the above thread, is this bad?

My tuner has a Performance tune, it requires either 91 or 93 Octane, however. Based, again, on the issues in this thread, would I be better off changing to the "Performance" tune and running the higher octane all the time. OR; am I "ok" where I am with the 87 tune running 89 octane.

I am a little confused about all this and would appreciate any feedback.

Thanks!

 

Ram4wd, even though your tune only requires 87, I would still go with the 89 like the manual recommends. As stated by several people, the $4 difference in price per tank is not worth the possibility of damaging your engine. You won't damage your engine by running 89 with the 87 tune. I'm curious though, why did you put in the 87 tune if you aren't buying the less expensive gas? Are there other "benefits" to that tune?

 

SOS:

On the PowerPro tuner my choices are 87 tune, Stock, or Performance (91 or 93).

I originally put in the 87 tune assuming I would then be safer then running 87, but now apparently not so. However, even with the 87 tune I could feel a noticeable change in the way my truck runs. With the 87 tune and running 87 the truck was "stronger". When I changed back to 89 octane I noticed even better "performance".

Since I have an '06 1500 I have the MDS system. At lower speeds the truck seemed "weak" AFTER putting the 87 tune on it is much stronger, takes less effort to get going and to keep cruising. In tough hilly situations it pulls significantly stronger with less throttle required.

Now as I stated in my earlier post, I am beginning to really think about changing to the "performance" tune; might even see a little mileage improvement as well????

 

If it has a 87 tune, then it is robbing power and allowing you to run 87. 89 for the stock tune and 91 if you want more performance/mileage using 91 octane.

I always ran 89 before my Predator and had no issues. I now run 93 with a 93 tune and it runs much better and gets better mileage with the MDS turned off now.
I get about 20mpg on the highway and around 15 in town, unless I am testing to make sure that my extra 20RWHP are still there

 

Hate to bring up a old thread but here is a thread with some pics of someone use 87 too much and too often.....and now he knows it too


http://tinyurl.com/26fd7r8

 

Going from memory here (and that's getting old also), I think that 85 octane is common in very high-altitude areas like western Colorado. I seem to recall seeing it on my way from Denver to Moab, Utah about 10 years ago.