Will high octane really damage my engine?

Wow. I always thought it could do damage if you went the other way (putting lower octane gas into an engine requiring high, although today's engines can compensate for it). Years ago, when gas was cheaper (heh, heh. remember when?) I would sometimes put higher octane gas in my car, even though it served no purpose whatsoever in my car. I'm curious to know the answer to your question.

It is possible BUT not very likely. The higher octane fuel additives MAY not burn off as well and could result in carbon deposit buildup on the heads. Easy solution would be to use some cleaner every few thousand miles to prevent it from occurring.

Oh and thank you. Keep your head down.

That part is really debateable because some modern hi compression engines really need more than 87 to run at their fullest potentail and will run better and get better fuel mileage with it. While maybe they might not all gain, all for my vehicals do especailly in hot weather and even my wife 4cyl 2000 Cherokee runs noticably smooth at speed and picks up 1 or 2 mpg as well when she uses it during the warmer months. Besdie at today prices it is only 4 to 6% for premium and I gain more than that back in performance and MPG in my cars so it is actually cheaper to run premium for me.

Or the good Polish tune-up" Never had a car as a youngster that had any danger of caboning up, regardless what was used for fuel!!!

"jmc" wrote in message news: snipped-for-privacy@individual.net...

I wouldn't lose a minutes sleep over it. I imagine that your owners manual when talking about high octane is referring to 100+ octane racing fuel but, still I don't know why it would harm the engine. Higher octane fuel doesn't ignite as easily as lower octane fuel. With higher octane fuel you have a more controlled burn than with lower octane fuel and that is why you have detonation with low octane fuel because it so easily ignites = pre-ignition. With today's newer engines many have a higher compression ratio than they had 10 years ago. The computers on today's vehicles try to adjust for the lower octane fuel to keep them from the pinging pre-ignition. Back in the late 60's when you had such high horsepower engines coming stock in musclecars they were running 10:1 compression or higher and they had higher octane fuel at the local gas station. Now we've got the high compression ratios back in quite a few new engines and are using the computers to retard the timing so that they run on 87 octane fuel without damaging the engine from lack of octane. If the compression ratio of your engine is not high enough to require high octane fuel then you don't need it. 2 octane points above the normal premium gas here in the states will make next to no difference at all except your engine may run better and cooler and if it pinged on 87 octane fuel you will not have to worry about it pinging anymore.

Ben in TN

no

If you can find a lower octane in the facinity, what about diluting it evey couple tank-fulls.

IIRC, the problem with using high octane fuel stems from the computer. It seems that the longer burn time of higher octane fuel fools the computer into thinking that the engine is running rich and causes it to lean the engine out. Running lean itself is not a particularly good thing for the engine and will be reflected in a loss of power, not to mention heat which could cause detonation, another bad thing for the engine.

Where did you buy it?

Suddenly, without warning, TBone exclaimed (08-Jun-05 1:42 AM):

What, the truck? In the US, before we were posted here. Not California, though.

jmc

computer.

This could not be further from the truth and does not warrant further comment.

And those that cannot or do not explain there answers are usually full of s*it.

No, only those that claim thing that are without merit like premium being harmfull. I could go into a long explaination why but you have already made up your mind so it is would be a wasted effort but I would explain why to anyone else that honestly wants to know why.

Your typical warped logic didn't deserve any explanation. Heres your logic, high octane fuel causes the computer to lean the mixture which causes increased heat which in turn causes detonation (I assume you mean pinging). Somebody really needs to explain why this is warped to you?

First of all, I never claimed it, that would be the manufacturer who I would believe, knows far more about their vehicle than you do. Second, your childish response further proves that you really don't know WTF you are talking about here.

you want some real grins ?

check out his idiotic responses about GM AC in alt.autos.4x4.chevy.trucks " Leprechaun in Suburban AC unit"

and in alt.trucks.ford in "91 f150 towing capacity"

where his claim to his knowledge about the AOD is

" Probaly a lot more familar with transmisson and gear limitations than you think! I actually have a working 83 AOD in the barn right now. (pull from a vehical I junked out)"