This was inspired by the catalytic converter thread. Funny thing, I live out here in West Texas where we drill for that black gold and have a number of refineries. Now, you ask anyone out here who's been working in the oil field for more than ten years and they'll tell ya that all gas is the same, whether you're talking octane rating or just plain old brand of gasoline (Exxon, Chevron, Texaco, Fina, etc.). I've heard from many people that all the gas comes from the same refineries and stations just add whatever additives after that to their particular brand.

I find it interesting that out here, my car only runs well on 91 octane from Chevron (I used to use Texaco). All we have out here is 91, I think maybe there's one or two places you can get 92. I have to explain this to all my friends and various other people that my car WILL NOT run on anything else. I put maybe a 1/4 tank of 87 in it one time and it litereally died. I had to get a ride to Wal-Mart and get some octane booster to get it to run again. I have to explain that engine damage REALLY WILL happen if you run anything else in it. Now, I don't know what it is about Benz engine construction that makes them so sensitive to octane as well as brand. Anyone want to shed some light on this or give an opinion?

Well, first off, most major brands have their own " recipe " for blending gasoline.
A mixture of detergents, octane enhancers, etc.
Secondly, many people think that octane requirements of an engine are strictly related to compression ratio. Not so.
Some other factors enter into the equation such as, shape of the combustion chamber, shape of the piston domes, etc.
If a vehicle manufacturer says to use a higher octane fuel, do it!
If the engine could be operated EFFICIENTLY on a lesser ( cheaper ) grade of fuel, I'm sure the manufacturer would like to cash-in on that fact, being a selling feature and all.

I've always heard the compression story. That's the one most commonly given. Thanks for the additional input. I put premium in all my cars, with the exception of my YUKON I used 89, because both cars I've had recommended or required it.

no flaming please

We use to always use premium (93) but when the sulfur problem came about, our dealer said to use a tank of 89 once in a while to get rid of the sulfur smell. You know what, we did and it did get rid of the smell! Call it crazy, but it worked.

I only use 93 now as the smell has not come back since, but even with those few tanks of 89, the engine still ran fine, no problems what so ever. that was a few years ago.

my .02