Dodge Ram 6.4 Heavy duty V-8 gas

I have really have had no problem running 87 octane in my 2016 Ram 2500 with 6.4 hemi and 4.10 rear. I generally run 87 when not towing. When towing my 12K fifth wheel I try to use 89 octane when available. At least one time I can remember no 89 octane was available and I needed gas when towing. I filled with 87 octane and continued towing the fifth wheel. The manual does say 89 recommended and 87 acceptable. I have found no real difference in either performance or mileage. Hope this helps.

Had one for a while before moving up to a diesel when we upgraded to a fiver.

I tried to use 89 or 91 when towing, mostly 87 the rest of the time. To be honest, like kzspree, I never saw much difference between the them, whether towing or not. Kept at it mostly for peace of mind.

I liked the truck, and really liked the engine.

From pg 542 of the manual:
STARTING AND OPERATING 6.4L Engine
This engines is designed to meet all emissions regulations and provide satis- factory fuel economy and performance when using high quality unleaded gaso- line having a posted octane number range of 87 to 89 as specified by the (R+M)/2 method. The use of 89 octane
“Plus” gasoline is recommended for optimum performance and fuel economy.
While operating on gasoline with an octane number of 87, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see your dealer immediately. Use of gasoline with an octane number lower than 87 can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty.

Mortimer Brewster wrote:
From pg 542 of the manual:
STARTING AND OPERATING 6.4L Engine
This engines is designed to meet all emissions regulations and provide satis- factory fuel economy and performance when using high quality unleaded gaso- line having a posted octane number range of 87 to 89 as specified by the (R+M)/2 method. The use of 89 octane
“Plus” gasoline is recommended for optimum performance and fuel economy.
While operating on gasoline with an octane number of 87, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see your dealer immediately. Use of gasoline with an octane number lower than 87 can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty.

When I run 87, i get the knocking sound and less power. I just end up running 89 all the time. the cost isn't that much more and the engine runs much smoother.

I suggest if you are around sea level and in hot weather towing that you buy premium. Ex: if you pull Davis dam I suggest you get premium.

Anything above 3K or so and in cooler weather I would not worry about it.

The down side is you're going to lose a handful of HP and the engine "could" run a "little" hotter.

It's possible the issue with using low octane fuel when towing is the slow build up of carbon.
So saving a few dollars here and there may cause you big headaches in the future.

I have the higher HP version of that eng in my SRT. I'm not worried about a few bucks every fill-up so it always gets the good stuff.

clarkster wrote:
Says premium gas is recommended?..

What is the downside if regular gas is used?
Some folks are telling me nothing other than a slight decrease in power?..

Ram dealers in my neck of the woods are selling 2500 Ram quad cab 4x4 for $38K.....

I sure could use a boost in ponies towing 5500# travel trailer with a 5.0 Ford half ton.

My 2017 with the 6.4 says 89 recommended but not required. Runs and tows fine with 87 for me.

My Subaru with the H6 on the other hand says minimum 91 octane and runs very poorly on anything less.

Premium gas does not have booze in it. The booze reduces power and mileage. I run a 8.1 L and the difference between booze and no booze is noticeable.

There is no reason to run booze in fuel at all except for income generation.

Consensus is.......go for 87......89 when under load.

Sums it up nicely......thank you

Seamutt wrote:
Premium gas does not have booze in it. The booze reduces power and mileage. I run a 8.1 L and the difference between booze and no booze is noticeable.

There is no reason to run booze in fuel at all except for income generation.

Not true, some places add ethanol no matter the grade...