Question about Chevron, ethanol:
 

A while back I had heard that Chevron gasoline did not contain 10% ethanol like most others. Is that a wive's tale? I tried to buy it on the theory that car would run better/get better mileage/etc...

So Sammy, (or any other fuel experts), is there any real difference in the major brands in CA. these days? I put in Shell last week and could swear that my car ran better. (91 octane, stock 996). I let it run dry before fueling, so each tank is fairly pure of one brand. Anyone know? TIA. :cool:

Denis - I use Chevron. Regular for the truck, super unleaded for the 911. I use it mostly for the Techron. The 911 runs better on Chevron than Mobil, FWIW.

My question is what ethanol is supposed to do for the gasoline, and what are its effect on an engine, particularly an older engine with no electronics, but instead carburetors?

It has less BTUs than gasoline, so you get worse mileage= pay more.

Aren't there readings on the pumps that show how much ethanol is in the gasoline? Maybe I'll check those out. I know in my neighborhood, Shell is less expensive than Chevron, so maybe there's less ethanol - I don't know. But if your car runs better, I might give Shell a shot and see what it does for my car.

I also wonder if all gasoline contains Techron.

Been discussed lots. Do a search. Here is a good thread to get you started (i.e. worked up). http://forums.pelicanparts.com/porsche-911-technical-forum/385016-effects-ethanol-gas.html

These days there doesn't seem to be any rhyme or reason. Most Chevrons around here have the sticker indicating their fuel may contain up to 10% ethanol. There's a Shell station in town that has the highest prices around, and also indicate ethanol in their fuel. Exxon seems to be ethanol free from what I've seen. Might be different depending on region.

Thanks, Harry D. I remember a little bit about that thread. Time for a refresher course. SmileWavy

Blending in ethanol (or equivalent) is mandatory in Ca. since the outlaw of MTBE. Not sure of the exact percentage, they've upped it a couple of times but 10% was the last I had heard in Ca.

There is usually no difference in gasoline from one station to the next or one brand to the next, in fact the gas you bought from shell could have been refined by Chevron, exxonmobil, valero, or anyone else this week and by someone else next week. The majority of gasoline is sold to wholesale distributors who sell it to who knows, after the correct additives are mixed in. The difference is in the additive package and that difference is very small.

fwiw In school I dyno'd a carb'ed 351 ...full load and throttle, measuring BSFC w/ gas, then 10%ethanol, then 10% methanol... Surprisingly, there was no drop off in power, as expected, with alcohol fuel. The speculation is/was the alcohol made up for the lower energy density by helping to provide a more complete combustion. (better vaporization)