I'm not trying to step on your toes Jimmy Dean, you're on the right track!

I believe you are referring to flash point. Flash point is the temperature at which a product gives off enough vapors to burn. Gasoline flash points go below -100 degrees F, meaning it will burn anytime, under any normal conditions (it would be very difficult to get it below -100F). Distillates (Jet fuel, diesel fuel, etc.) have a much higher flash point. Jet fuel, which is kerosene, has a minimum flash of 108F. Diesel fuel minimum is 130F.

Higher octane gas still has an extremely low flash point, but the higher the octane gas will resist pre-ignition. Pre ignition is actually what you hear in "spark knocking". Spark knock is actually 2 exposions, each travelling in opposite directions. One prematurely, one from the spark plug.The causes can be many, but the most common are hot spots on the piston(from carbon buildup) igniting fuel on the intake stroke, the other from ignition during the compression stroke (high compression engines). When these 2 explosions meet, it creates the knock that you hear.

 

Higher quality fuels like Shell, or what I use Phillips, have the detergents etc in them that will keep the fuel system clean without the use of additives. I used to watch as people filled up at a cut rate station and poured many dollars of additives in their tank. The customers at Phillips rarely bought an additive and the cans sat on the shelf gathering dust. The cut rate station sold cases of the stuff every day. When you looked at the cut rate customers cost of a tank of fuel it was over double what they would have paid if they filled up at Phillips, -it was quite comical.

Nowadays the lower cost fuels have methanol or ethanol blended with them in order to enhnace their octane rating. Mixing gov't subsidized cheap alcohol into the fuel lowers their cost per gallon, it also lowers the energy per gallon of the resulting mix which lowers your mileage. When they really want to lower their costs they add in even more of the alcohol than they are supposed to. Of course they are supposedly allowed 10% but they should only add 5% max. Anything over 5% puts another drain on your wallet because it destroys fuel hoses, injector o-rings, corrodes fuel system parts, clogs injectors, destroys fuel pressure regulators, rusts tanks, clogs filters, and of course lowers your mileage due to efficiency losses and misfiring. It is a lose-lose-lose situation

You should never use a higher octane rating fuel than your engine is designed to require. If it won't run on the fuel it was designed for it needs repair or a switch to higher quality fuel (not higher octane, -just a better brand). Using a fuel with a higher octane rating than it was designed for will actually lower your mileage and increase your fuel cost per mile considerably.

 

In many places, all fuel has alcohol added to reduce pollution.

 

Poor suckers... I guess all you can do is move out of those areas and leave them to the idiots in charge.

I buy 100% gas only, -unless I am burning thru it quick on a trip.

I found out that running alcohol fuel in your lawn mower etc will eat it up fast also. For several years my wife and kids would pick up lawnmower fuel around the corner at the QT or 7-11. It had alcohol in it which would make large quantities of water appear in my lawnmower tank. I got tired of ripping the fuel system apart every time I wanted to use the lawnmower and finally realized where it was coming from. I now drive a little farther for mower gas but I don't have problems with water anymore either.

I bought another mower the other day and the instruction manual forbids using any fuel containing alcohol in it! I guess they don't sell those mowers in some states.

 

What do you know that the rest of us "suckers" don't (I'm offended by the way )? Where do you get your gas?

only kidding about the offended...

 

I've been burning a 5-6% blend in everything I own for ~5 years, with no ill effects.

 

How the heck do you guys know the blend ratios of what you're buying? Last I checked, the gas stations don't exactly publicly post this information!

I do know that as winter approaches, I know when the gas stations change their blend because my MPG's go down. I can normally tell you at exactly what fill-up my gas station's blend changed, and came back in spring/summer. But other than constantly monitoring my MPG's, I know of no other way to determine the quality/blend of the fuel I'm buying. So what's your trick guys? Teach me!

 

When alcohol was first introduced into fuels the stations had to post the content by law but somewhere down the line the rules were ahh "relaxed"...

You have to ask the right people, do research, and look sharp at the pumps. Many of the stations will disguise the fact that they have alcohol by calling it HTA (maybe High Test Alcohol??) or other things. I buy my gas back here in Kansas from Phillips 66 and it is 100% gas at the stations I go to. I can't vouch for all of them tho.

5-6% isn't too bad. It will still draw moisture into your equipment and lead to corrosion but at least it won't eat up gaskets and seals. The problems really mount up when you approach 10% and add engine heat. 10% won't eat gaskets etc at room temp but the underhood environment is a little warmer than that.

 

The place I usually gas up has "5.5% ethanol added to all grades" posted on the pumps.