Was told the newer 6.4L Hemi uses 87 Octane and the 5.7L uses 89 Octane.
Thinking about pulling a 5th Wheel Trailer and was wondering if this is true.
Happy trails,

 

You can run the 5.7L off 87 octane with no issues, you just might not get full power out of it since it may have to detune a bit if the 87 causes any knock.

 

Considering that the price difference between 87 and 89 octane is typically 10c per gallon which amounts to about the price of a cup of coffee for an entire tank full of fuel, why even risk it?

Many of the programmers offer programs designed to run 87 octane safely. But if that would be the primary reason you would invest in a programmer it does not make much financial sense. A typical programmer runs $300-$400. If you again think back on that 10cent difference in price for 87 vs 89 fuel it would take roughly 150 tanks of fuel for the programmer to pay for itself. That could mean years depending on how often you fill up. And don't forget the potential of a voided warranty for using a programmer.

Just my 2c.

 

As with ths 5.7, the specs on the 6.4 states 87 is ok, 89 recommended. I'd personally run 89 in either all the time but no doubt anybody towing, especially a 5th wheel shouldn't even consider 87 octane.

BTW, the 3rd gen I just sold neved saw a drop of 87 octane gas in it in 10 1/2 years. Matter of fact, since I tuned it in 2006, it never saw anything less than 92 octane...

 

My 2012 RAM 1500 runs like crap on 87 octane.The minimum I can run in her is 89 for power and high MPG.Running the 92 with a bottle of octane boost makes it run like a F-22 in full afterburners but gets high enough mileage that a tank of gas last a month.Although being retired law enforcement I try not to treat her to rough unless I need to avoid the local kamikazi pilots in east Texas.
Now that fuel prices are dropping so fast I highly recommend the best grade of gas you can get.Right now the 92 octane is $ 3.19 per gallon here.
Hopefully this will help those seeking more power and higher mileage.

 

I know this will cause an uprising by those on here who have always run 87 octane and not had a problem (yet) but I've had the opportunity to rebuild a couple Hemi engines and the ones where the owners profess to using only 87 octane have a lot more scoring and other evidence of constant pre-detonation.


That's why I tout using 89 octane unless you change the stock tune to one specifically for 87 octane fuel...

 

Mine still seems to run fine on mostly 87 octane, 106,000 miles and counting.


Guess if the engine blows up I'll get to take advantage of that lifetime powertrain warranty

 

and I know people with more miles who have never run anything but 87. My only point is that the few I've seen fail, at the cylinder level, all clearly show signs of pre-detonation and that if it was my vehicle what I would run.


The book clearly states "87 - OK, 89 - preferred", I don't begrudge anyone running 87, although as with the OP's question, I do firmly believe you need the extra couple of octane points if towing heavy.


BTW, oldjeep, take this from someone in the industry, Fiat ownership seems to be taking a page out of the Ford book and are fighting EVERY substantial warranty claim. Keep those records for EVERYTHING!!!

 

No problem there, the dealer does all the engine/trans service on it. I can't change the oil as cheap as I can have them do it.

 

If it runs like crap on 87, then there is something else wrong with it. It was designed to run on 87 and you are the first one to claim that it runs like crap on 87 on this forum.

Do whatever you want but running 92 does nothing more than running 89. Also octane booster can damage sensors and catalytic converters.