Fuel Question (Octane)

[alphalanos]

I have an 02 Daewoo Lanos HB and when I drive fast it uses alot of gas. So a few days ago I absentmindedly put 98 octane premium in the car while it still had about 1/4 tank of reg unleaded. I heard that this was bad for the engine(mixing the two fuels) Also, I cant really tell but does 98 octane give better mileage?

[MioCLK]

higher octane gasoline WON"T improve you gas mileage
there is nothing to benefit from using a higher octane gasoline
just use what the owner's manual tells you

[sideshowrich]

The higher octane gas won't make any difference unless you have a tuned/built engine. With higher compression or forced induction, using the higher octane stuff is good (if not required) to avoid detonation. And don't worry about mixing the two different fuels, won't do anything.

[lwsurf84]

What is another good fuel stabilizer other than Fuel Power and the stuff that auto zone sells. Because I have a diesel engine and diesel gas is dirty so is there any thing out there to clean it up a little?

[disco192]

Adding better fuel wont do anything except empty your wallet on a daewoo.

Mixing wont harm anything eihter. Buy better gas from better stations, not higher octane from crappy ones. Stick to shell and chevron, stay away from racetrac. It will make your engine happier and your fuel filter

[SaabJohan]

Newer cars will change boost/fuel/ignition depending on the fuel. If the car isn't turbocharged it can't of course change the first one. By changing fuel and ignition it can change the octane need and of course the efficiency of the engine. Therefore a higher octane can give a better mileage, it's just to try and se how the fuel consumption will be affected. In worst case nothing will happend.

There is no danger to mix diffrent octanes, sometimes this is even done at the gas station to give an octane between for example 98 and 95.

Unless you own a refinery or some impressive filters the only way to "clean" diesel fuel is by buying a cleaner diesel from the beginning.

[SilverFeniks]

So there's really no reason to put in gas over the recommended octane?
I have a 98 VW Golf, have used 87 since I got it this summer, but have been thinking about putting 89 in it ... but if there's really no advantage in economy/performance/engine life I guess I should just stick with 87?

[KC Ron Carter]

will provide less thermal efficiency to get a more stable flame progation.

Yep, more octane in pump gasoline will provide less miles per gallon.

On race gasoline or special mixes all bets are off.

Only use what you need.

Later,

[SaabJohan]

Originally Posted by KC Ron Carter

will provide less thermal efficiency to get a more stable flame progation.

Yep, more octane in pump gasoline will provide less miles per gallon.

On race gasoline or special mixes all bets are off.

Only use what you need.

Later,

A higher octane fuel will only provide a better protection against knocking. This means that an engine can run with higher combustion pressure/temperature. This can mean a leaner mixture and an advanced timing which increase efficiency. Energy content is the same and density is about the same, the high octane fuel can have a somewhat higher density.

An engine needs about 15 minutes to adapt to the new fuel, a few hard slow accelerations should be done.

[Sluttypatton]

Everyone has pretty much said everything that needed to be said, but I thought I would add that about a year ago shell fuel was really damaging fuel pumps. I am not sure if it still does this, but I stay away just to be safe. A couple of fill ups at shell won't do any significant damage, but if your a regular shell customer, you may want to look into it.