Higher Octane Fuel

[J Mac]

does anyone use a higher octane gas in their tow vehicle when towing?
Is it worth it?

[padlin]

For my F150 Ecoboost, the manual says to use it when heavy towing. I don't consider these heavy and have not tried it. If I run into performance issues I'll give it a shot, $3.70 a gallon is high enough.

[rbryan4]

Originally Posted by J Mac

does anyone use a higher octane gas in their tow vehicle when towing?
Is it worth it?

If you have engine pinging, knocking or other problems under a hard load, then the higher octane can help, whether you tow or not. Let your ears decide.

Run the fuel that results in a quieter engine. If regular works fine, why change it? There is no advantage to burning higher octane in an engine that runs quiet and smooth.

At higher elevations it can actually hurt mileage, because you don't need a higher octane at high altitudes. It's one of the reasons why gasoline refiners sell higher octane at low altitude, and lower octane at higher altitude.

[cpaharley2008]

I use the mid range 89 in my Hemi, recommended. Although out west used several tanks were with E85 without any issues.

[Brian B-P]

We have always run regular in everything, including our Toyota Sienna tug... except the race-prepared Honda when we had the ignition advanced for better high-rpm performance.

Originally Posted by rbryan4

If you have engine pinging, knocking or other problems under a hard load, then the higher octane can help, whether you tow or not. Let your ears decide.

The problem with listening for a need for octane is that the engine management systems listens much more sensitively than your ears, and may be retarding ignition (or limiting boost if a turbo) to prevent preignition... if so, your ears won't tell you there isn't enough octane for ideal operation.

Originally Posted by rbryan4

If regular works fine, why change it? There is no advantage to burning higher octane in an engine that runs quiet and smooth.

I agree that it is a waste of money (and natural resources) to run higher octane than required; however, I don't think "quiet and smooth" is reliable proof of a lack of need.

[Brian B-P]

Originally Posted by cpaharley2008

I use the mid range 89 in my Hemi, recommended. Although out west used several tanks were with E85 without any issues.

E85 (85% ethanol / 15% gasoline) has an octane rating comparable to or better than premium gasoline... not that it personally matters to me, since E85 is not available here (there are perhaps three E85 stations in all of Canada, and all of them are in Ontario).

[rbryan4]

Originally Posted by Brian B-P

We have always run regular in everything, including our Toyota Sienna tug... except the race-prepared Honda when we had the ignition advanced for better high-rpm performance.


The problem with listening for a need for octane is that the engine management systems listens much more sensitively than your ears, and may be retarding ignition (or limiting boost if a turbo) to prevent preignition... if so, your ears won't tell you there isn't enough octane for ideal operation.


I agree that it is a waste of money (and natural resources) to run higher octane than required; however, I don't think "quiet and smooth" is reliable proof of a lack of need.

Well, assuming you have good ears....lol

[CADreamin]

We normally use CA regular for our Tundra. I make the differentiation because, when we were in Idaho and Wyoming, we noticed that the octane rating for their "regular" was lower than in CA (85 vs. 87) so there we used mid-grade.

[rbryan4]

Originally Posted by Brian B-P

E85 (85% ethanol / 15% gasoline) has an octane rating comparable to or better than premium gasoline... not that it personally matters to me, since E85 is not available here (there are perhaps three E85 stations in all of Canada, and all of them are in Ontario).

Except E85 has less energy content than the same amount of regular gas. IMHO Ethanol is one of the worst things to happen to fuel. Its heavily subsidized here in the states, and is at least partially responsible for higher food costs. Ask any reputable San Antonio mechanic ( I have) and you will get an earful about how E15 is ruining engines. Its also the reason my lawn mower, chain saw, gas trimmer and go-kart won't start if left sitting for more than a month without fuel stabilizer. The ethanol gums up the carb jets, fuel lines, and pretty much everything it touches. And the coup de gras is that our tax dollars are paying for it. OK....rant off. I feel better.

[Brian B-P]

Originally Posted by rbryan4

Except E85 has less energy content than the same amount of regular gas.

I agree; my comment was only about octane. Aside from octane rating, alcohol (whether ethanol or methanol) in gasoline is a large and complex subject.

Also, since energy content has been mentioned, octane rating is unrelated to energy content; premium (meaning higher octane) gasoline does not inherently have any higher (or lower) energy content than regular gasoline.

Just to be sure that everyone understands the notation, "Exx" fuel is a mix of gasoline with ethanol making up xx% of the mixture (so E15 is 15% ethanol and 85% gasoline).

For the diesel drivers, a similar notation is used for "biodiesel" content, so B5 and B20 are 5% and 20% (respectively) biologically-derived fuel... not that those diesel drivers would read this because they don't care about octane ratings, since the measure relative to them is cetane rating; diesel fuels are not sold with various cetane levels.

[Jubal]

Legislation is being proposed in the US to list the cetane rating at the pumps.