Octane and towing

[sourdough]

Just thought I would throw this out since I'm just sitting here.

When I bought my Ram 2500 6.4 (2014) I just started using 87 octane. Didn't think much about it and it seemed to do OK. First couple of trips to FL seemed I always got bad gas with water or something in it causing the truck to hop and skip. I would clear it up and switch to 89 octane and things seemed better. A couple of months ago I heard "rattling" from the engine at low speeds and slight acceleration - sort of like the rattling/pinging in the old days from low octane. I switched to 91/92 octane and have been running it for the last couple of months. First, the truck runs MUCH better. Secondly, and most appreciated, it tows much better as well. Not only does the truck pull better, BUT, I just ran from W TX to E of Canton, TX (about 400 miles) and averaged 10.4 mpg. This truck has never seen that. This stretch usually nets about 8.5 mpg. Runs better, pulls better AND better mpg. What's not to like? Fuel is about 30-40 cents more but with those benefits I don't really care. I used to think about octane back in my hot rod days and tune to it but I figured with all the computers and stuff running the truck it was probably immaterial....apparently it's not!

I thought I would throw that out since we've had lots of folks talk about their mileage with a gas truck; good and bad. Someone might want to try it out if it sounded like it would work for them. I'm going to continue using it; especially with the trailer behind me.

[slow]

Made the same discovery with my 2015 F250 6.2 gasser a couple of years ago. Since it is not a daily driver and only used for towing, I feed it premium only.


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[JRTJH]

The computers in modern vehicles can make up for a lot of reduced octane, but they can't work miracles. One thing not yet mentioned is the ethanol content in fuel. In many places, regular unleaded is 10-15% ethanol and premium has no blended ethanol content. That alone would improve the fuel mileage some. So there's more than meets the eye to consider beyond octane ratings.

[slow]

Good point about the ethanol content in regular and mid grade gas.


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[chuckster57]

When in doubt:

https://www.pure-gas.org/index.jsp?stateprov=NJ

That’s the page I was directed to, looks like you can look up any state.

[B-O-B'03]

When in doubt:

https://www.pure-gas.org/index.jsp?stateprov=NJ

That’s the page I was directed to, looks like you can look up any state.

Man, this is depressing:

189 Pure Gas Stations in Texas

As much petroleum related industry as we have here and this is the best we can do??

Maybe they are just not all listed ;)

-Brian

[linux3]

Man, this is depressing:

189 Pure Gas Stations in Texas

As much petroleum related industry as we have here and this is the best we can do??

Maybe they are just not all listed ;)

-Brian
764 in NY. Who'd a thunk.

[busterbrown]

My Hemi 6.4L loves premium fuel when pulling. On our trip down to see the total eclipse, I experimented with a tank full of 87 octane "regular" grade gas (e10) through Tennessee and the Carolinas. It was obvious to both my wife and I that the engine worked harder on hill ascents as the torque curve flattened. We fill up exclusively at Pilots on roads trips so the brand of fuel didn't change.

On the way back, premium octane fuel was used and the truck's characteristics change for the better under load.

I just read the 'fuel' section of the RAMs owners manual and it states "the use of 89 octane 'Plus' gasoline is recommended for optimum performance and fuel economy". It also makes reference to engine retardation and knock. "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".

I agree, it's well worth the extra few cents per gallon to have a truck running optimally under stressful conditions.

[Tinner12002]

I thought that Ram recommended using premium gas in the 6.4.

[jkohler70]

Engine manufacturers have been increasing compression ratios and combining it with port and direct injection to increase power and economy. Higher compression engines and turbos perform better with higher octane fuel.

One thing I do is avoid non top-tier gas stations unless I have no other option. This is from AAA - "Among brands tested, non-TOP TIER gasolines caused 19 times more engine deposits than TOP TIER brands after just 4,000 miles of simulated driving. Such carbon deposits are known to reduce fuel economy, increase emissions and negatively impact vehicle performance, particularly on newer vehicles."

[Desert185]

The wife’s turbo only gets 91 octane, and a dose of Techron once or twice a year. Diet is important for the both the driver and the vehicle. Consuming cheap is false economy.

[B-O-B'03]

The Cobra, being supercharged, gets nothing but 93, the GT and F150 have been fed a steady diet of 87, since new, with no issues.

I get from 10 to 12 MPG towing, seems like it is better in NM and CO, than TX (possibly an E10 issue, not sure).

-Brian

[mtofell]

I thought that Ram recommended using premium gas in the 6.4.

The manual says 89 is recommended but 87 is acceptable. I feed mine 87 as a daily driver but will go higher octane when towing.

This summer I was up in the woods and found a station with only 1 pump and it was non-ethanol premium. Wow, did the Hemi ever love that! Mileage was amazing and seemed more powerful too (could have been my imagination though).

[chuckster57]

More interesting reading:

https://www.fueleconomy.gov/feg/octane.shtml

[mfifield01]

The 5.7l hemi has the same recommendations on octane. I put 89 in it when I plan on towing. After selling my boat and before purchasing the TT, I put 87 in on occasion. I didn't notice much difference, but never pushed the engine.