Using Premium Gas To Clean Your Engine

[Lexington]

Hi All

Recently my sons 96 Ford Ranger didnt pass smog. So I took it to my mechanic to have it inspected to see why it failed. On my way to there I picked up some CRC Guarantee To Pass Smog. I showed this to my mechanic and he advised against using it because the chemicals in it are harsh and can eat away at the plastic liner in gas tanks and seals and create a bigger problem. Instead he recommended that my son fill his tank up with premium gas and go through a whole tank and that should do the trick. He said the higher octane will clean out some of the carbon build up. We tried it and it worked. However, I’m not exactly sure why. Does premium gas burn a little hotter which helps burn off the carbon? I read that premium gas usually have more detergent than regular gas. So was this the reason it worked or a combination of both. If anyone can explained why this work I would appreciate it.

Thanks

 

[spaikmos]

Interesting... I've never heard of higher octane itself cleaning stuff, but since people use seafoam to clear carbon deposits, maybe the higher octane has a similar effect?

 

[trainman605]

When I purchased my John Deere riding mower some 14 years ago the dealer said I should run premium fuel in it. To date I have never had a running problem with it, starts and runs just like the day it was new. He said the higher octane would help prevent carburetor and carbon problems for these engines that are not fuel injected and designed for today's new design engines. I'm pretty much a believer in this train of thought, as I have used the high-octane fuels in all my nonfuel injected engines. I have no idea on if it would work in older model vehicles, but using higher octane fuels starting today I would think it would correct any problems you might have today.

 

[johnbt]

When I was growing up in the '50s and '60s some folks would run a tank of Shell Premium through their cars every few months or once a year because the Shell Premium supposedly had a much better additive package than the regular cheap gas. My father used Esso - later Exxon - and didn't seem to have to resort to using Shell.

Some folks made it a habit to buy gas a different stations under the assumption that different brands had different additives that would clean different stuff. I don't know, but what could it hurt.

 

[fourwd1]

Change the engine oil right before you go back for a retest.

 

[2008sr5]

Hi All

Recently my sons 96 Ford Ranger didnt pass smog. So I took it to my mechanic to have it inspected to see why it failed. On my way to there I picked up some CRC Guarantee To Pass Smog. I showed this to my mechanic and he advised against using it because the chemicals in it are harsh and can eat away at the plastic liner in gas tanks and seals and create a bigger problem. Instead he recommended that my son fill his tank up with premium gas and go through a whole tank and that should do the trick. He said the higher octane will clean out some of the carbon build up. We tried it and it worked. However, I’m not exactly sure why. Does premium gas burn a little hotter which helps burn off the carbon? I read that premium gas usually have more detergent than regular gas. So was this the reason it worked or a combination of both. If anyone can explained why this work I would appreciate it.

Thanks

This honestly kinda seems like bad advice overall (granted I'm a stranger on the internet, and he's a mechanic).

"Premium" gas, aka 92(ish) octane gas isn't really any different than regular at the pump. The higher octane means that the gasoline is more resistant to premature detonation. It doesn't have anything to do with the additives that are added or its "cleaning" properties.

Just one example, but lets say I had a turbo charged vehicle. Turbo charging is going to raise your incoming air temperature (IATs) vs a naturally aspirated engine which means that the internal combustion temperature is higher. If you are running regular gas (aka, 87 octane), you are more likely to experience premature detonation (cylinder igniting before it is supposed to) and your ECU may pull spark timing - reducing efficiency and power. You would want to run a higher octane fuel to prevent premature detonation as the higher octane has additives that allow it to handle higher cylinder temperatures. Some NA engines still require premium for maximum performance-these vehicles are typically tuned by the OEM for 92 octane (Inifinti is one car manufacturer IIRC)

With this said, especially at less reputable gas stations, regular may not be as pure as "premium". This is mostly speculation and if you stick to gas stations that don't look run down, you probably won't have a problem.

Long and short, using higher octane fuel isn't going to clean a fuel system. All the plastic in your fuel system is fuel rated, and isn't going to react with gasoline and other solvents.

Source: https://www.eia.gov/energyexplained/gasoline/octane-in-depth.php

 

[spartacus]

Shell, Chevron and Sunoco top tier gas have their own additive formula. They add detergents, Antioxidants, Metal Deactivators, and Corrosion Inhibitors etc.

 

[trainman605]

I wash my vehicle once a week if it needs it or not, what I'm trying to do is keep the body surfaces clean and help prevent drag to increase fuel mileage. So far it must be working as I get 23 mpg on the highway at 65 mph and I use the 87-octane stuff. :eyebrows: