Which fuel to use when towing heavy loads ?

[T-Town-Z]

Occasionally I tow a trailer with heavy equipment on it. I was wondering what fuel would be better to use at such times due to the load on the engine. E-85 ethanol or premium gas ?

[14 Silverado]

I run 89 in mine all the time never have a problem towing across country with it.

[POS VETT]

If your truck was an FFV and E85 was within reasonable distance, use it. Otherwise, 93-octane gasoline would provide a better resistance to knocking. The question is the effectiveness of using high-octane fuel so infrequently, i.e. mixing in the 93 when the truck has, let's say, 7/8 tank of 87.

 

Personally, in my '16 with 5.3l (not an FFV), I use 93-octane gasoline regularly and I mix in a few gallons of E85 to bump the effective octane rating.

[pm26]

Premium fuel is always better when doing heavy towing. Higher octane allows the engine ECU to advance ignition timing more for more power and performance. E85 is a good choice as well because of its high octane. However, expect much lower mileage with E85 as it has less energy than straight gasoline.

 

If you use regular gasoline (87 octane) for heavy towing, expect worse fuel economy and worse performance. This is due to the fact that ignition timing will be retarded much more by the engine computer to prevent preignition.

[T-Town-Z]

Normally I just run 87 octane. But when I know I'll be pulling something heavy, I've been using Ethanol, and yes the mileage really does take a dump with that in the tank ! I'm just not sure which fuel would provide more power and detonation resistance.