Does Octane Rating Affect Towing Power/MPG?

[lagman]

I've been running the mid-grade 89 octane ethanol blend since that is always the cheapest here in Iowa. I'm wondering if I would see any noticeable bump in towing power or mpg if I go with the regular 87 octane non-ethanol or 91+ octane premium grades. Does anyone have any real experience?

Thanks,
Dan

[DocBrown]

You will only see an increase in power and/or mileage if your vehicle's manual specifies that you can run 91 octane as an alternative. In other words, is your vehicle a "premium optional" vehicle. If not, then spending any more money over the cost of 87 is throwing money away. Even if you have a premium optional vehicle, more often than not the return is not worth the extra money.

[3'senough]

I have a flex fuel vehicle and the ethanol is worse on fuel economy as a direct result of power loss from it's burning vs dino. If the ethanol is .55-60 cents cheaper I will run it but I loose 2mpg as a result. While towing I would think that the 89 dino with the standard 10% mix would result in better MPG, but you need to figure out the difference in cost.

Dino will provide more power while towing vs the ethanol which may elevate the numbers even more vs daily driving comps. I tow with a diesel and have no towing numbers other than regular driving on my flex fuel vehicle.

From what I've read you should not fluctuate constantly between the 2 and if you change do at least a half tank fill before doing so or your computer will not be able to optimally adjust your engines settings. Also you need to run at least one tank of dino every 3K.

[lx22f/c]

When i tow my trailer i use the premium 91 octane it does give a little more power. No increase in mileage but deff more power. It does cost more but i use it.

[lagman]

Originally Posted by DocBrown

You will only see an increase in power and/or mileage if your vehicle's manual specifies that you can run 91 octane as an alternative. In other words, is your vehicle a "premium optional" vehicle. If not, then spending any more money over the cost of 87 is throwing money away. Even if you have a premium optional vehicle, more often than not the return is not worth the extra money.

From my owner's manual:

"use unleaded gasoline. (octane rating 87 [Research Octane Number 91] or higher)"

So I assume I have a "premium optional" vehicle..

[DocBrown]

Originally Posted by lagman

From my owner's manual:

"use unleaded gasoline. (octane rating 87 [Research Octane Number 91] or higher)"

So I assume I have a "premium optional" vehicle..

That's interesting. Clear as mud. The manual for my Chevy HRR and my past Cadillac both were very clear that they can run premium. Best you can do is run a couple of tank fulls of each without towing and see what your mileage is and how the power feels. It'll only cost you a couple of bucks to find out. I can tell you that when I run premium in my HRR I get slightly more power at freeway speeds and slighly better mileage. Enough to make it worthwhile so long as premium isn't more than .20 a gal more than regular.

Originally Posted by 3'senough

I have a flex fuel vehicle and the ethanol is worse on fuel economy as a direct result of power loss from it's burning vs dino. .

With 10% ethanol people see results all over the chart. I don't see much difference myself, but if you have a flexfuel vehicle and run E-80, there will be a dramatic difference in mileage, for the worse because of the lower energy output of Ethanol. Your manual will also tell you to never tow with E-80. However, all of this is academic, the OP is asking about Premium vs. Regular, not E-80.

[Nighthawk 96]

Manufacturer of your truck recommends a certain octane fuel. Horsepowr and torgue are specified with that grade of fuel. You are likely wasting your money on a higher grade fuel. I have found with older vehicles that mixing one half premium and one half regular will be necessary to keep the engine from knocking. I use Ethanol free fuel in anything with a carburator like a generator or motorcycle since Ethanol may gum it up.

[Threebutchers]

I cant tell you if it helps or not. My TV is factory spec'd for Premium, but I have NEVER run premium since it was new UNLESS I am towing....in which case I ramp up to a full tank of premium. It makes me feel better - but there are so many variables (head winds, terrain, weather) and so drastic a drop in MPG....you would have to tow quite a bit to average out any performance gain.