Question: Reg Unleaded Vs Supreme

I heard somewhere once that if you use regular unleaded gas for everyday driving, that you should put the special supreme (the most expensive stuff) gas in once a month to clean the impurities out of your system. I know they make actual stuff you can buy that will theoretically clean your headers and injectors and stuff out if you pour it into your gas thank, but will this budget way work? If I put the supreme stuff in once a month will it actually clean my fuel system out? Mind you, I'm not driving a Shelby Cobra or anything... just a big ol' gas-guzzling Jeep... but still, if putting Supreme in once a month will keep it running longer and better, then I'm all for it...

I don't see that helping. Premium is for high performance cars not cleaning. I'm not a mechanic but that sound like something the Exxon's of the worls started to get you to pay an extra $.15/gallon.

I was told by some racing mechanics if you stick with the mid grade, you wont even notice any fall-off from the super. It has to do with burning off the carbon build up from your valves, something the lower gade gas will not always do, depending on the quality of the gas you purchase.

The difference between regular unleaded and supreme or plus is the octane rating. Certain cars require a minimum octane rating to run correctly (check your car manual, you'll find the reccomended minimum octane rating in there). That's why there are those yellow stickers next to the pump with numbers like 87, 89 and 93 on them. Using a higher grade octane gasoline isn't going to clean your fuel system (well, some gas companies claim that their fuels contain additives that clean your engine).

To clean carbon deposts and what-not that can build up because of the combustion of gasoline, people use fuel injector cleaner, which you can find at any auto-parts store.

The higher octane rated fuels are important for higher compression motors because it prevents premature combustion or knock. The octane rating indicates how much compression the fuel can handle before it ignites. Knock can damage your engine, not to mention power loss.

Supreme gas doesn't clean out your engine. If you hear engine knock (detonation) then you either have to increase or decrease your octane rating. Running a car at the wrong octain rating can be bad for it. To clean the carbon deposits you need to add the fuel cleaners with your gas, but don't put cleaners in an empty tank before you fill it, it can damage the tanks.

wow... awesome help... not only did i get my question answered but i learned a pantload... thanks so much guys!

Yep, all good advice.

Unless you are running a high compression ratio/the engine is pinging, you are wasting money on the high octanes. Some cars (namely performance and luxury) demand a higher octane, but a tank of 87 occasionally won't hurt it, if you absolutely have to. The engine's computer will adjust the firing and detonation pretty well.

No gas will truely clean your headers or injectors. Even the detergents added have a very marginal effect. The higher octane burns cleaner, but only slightly. So, 87 for the jeep!

Remember, it's all about money!

its the same exact gas it just combusts at a higher temperature

Unless your car needs supreme because it is a high compression motor you are just wasting money by using supreme vs. regular gas. As has been said before, if you want to clean out your fuel system, get a bottle of fuel injector or carb cleaner, and use that. Otherwise fill up that Jeep with regular and go puddle jumping

all good info! don't waste money on higher octane fuel if your car doesn't require it. Companies, like chevron, do claim cleaning additives and what not but that's your call if you want to spend the extra $. I have a friend who is an engineering major and he ws telling me that there is a negligable difference between 87 and 89 octane gas. He said you're better off just going with the 87. He said the combustion rates/processes (wahatever it is) between the two octane ratings is very similar. has anyone heard about this?

actually it might be between the 89 and 91, just reread whatshawnwanted's post above.
and i believe the remark about quality of gas.. watch where you buy your gas. I know quite a few mechanics who have attributed car fuel problems to people buying gas here in hawaii from a company called tesoro. They recommend chevron.

Using a higher octane than your engine needs will eventually result in carbon buildup. Then your engine might start pinging under load (pre-ignition or detonation) this is bad for your pistons and rod bearings. Use a bottle of fuel injector cleaner twice a year.