I burn avaition 100LL, but this question should apply to any fuel from 87 to 115 MON. I have fuel / synthetic oil premix in the tanks that 15 mounts old. I used stabilizer (15 months ago). Full talk, no evaporation, would you use it or drain and dispose?

I'd drain and dispose to just not have too worry about it.

I just did. It's so hard to dump aviation 100LL and 32:1 full synthetic. That mix is over $5 a gallon today. Makes me cry.

You should not run the 100ll straight.You need to mix some 91 with it.I mix it 50/50.Any fuel over 1 month i throw away.Thats just me though.I like to be safe.

It burns well in old pickup trucks. Why dump it?

Don't have an old pick-up and it would take a life time to put it thru my weed-wacker.

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Oh, yeah "You should not run the 100LL straight.You need to mix some 91 with it.I mix it 50/50".
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Why would you give such advice? My porting and fortmat requires 100 MON. I've been using this set-up sence summer 2001 w/o any maint. or problems.

What is it that you know about 100LL?

ABOUT AVIATION FUELS - Aviation gasoline (or "av gas") is blended specifically for use in small aircraft. It's also commonly used by many high performance engine owners because of it's high stated octane rating (usually 100-110) and the relatively low price compared to racing fuel. Unfortunately this fuel is not all it appears to be. Avgas octane is rated on a different scale than gasoline's intended for ground level use. What is 100 octane "av", is not necessarily 100 octane "ground level". Besides this, there is also a big chemical difference. Normal ground level race fuels are made up of gas molecules that have a "light end" and a "heavy end". The light end of the molecule ignites easily and burns quickly with a low temperature flame (as a piece of thin newspaper would burn). The heavy end of the molecule is not so easily ignited, but it burns with a much more intense heat (as an oak log would). This heavy end of the gasoline molecule is responsible for the hotter, more powerful part of the combustion process.

Small aircraft are constructed as very weight conscious vehicles. That's because their somewhat weak engines often have difficulty taking off with any extra weight. To help reduce this weight problem, aviation gasoline's are blended with no heavy molecule end. This makes a gallon of avgas weigh substantially less than a gallon of ground level fuel. Since small plane engines turn very low rpms and produce so little power, the omission of the heavy end is not a horsepower issue. However, for high output pwc racing engines, there is defiantly a compromise in power. This, despite the fact that many pwc owners experience the desirable cooler operating temperatures that avgas offers. In addition, some blends of avgas will quickly separate from some oils used in premix situations. For the above reasons, we do not recommend the ongoing use of 100% avgas, and we will not prepare any "avgas" engine kits.

Despite all this bad news, running avgas (accepting the slight power loss) is usually a better choice than burning down a high output engine on regular pump gas. In this situation, the best choice is usually a 50/50 mix of pump and avgas. That provides "some" heavy molecule ends for the engine.

i heard the story's about av gass being no good in high reving race engines ,due to the fact it is desined for slow reving planes .
but i ran it for years in a high comp drag bike and found it beter than any other fuel that i tryed (c12 c14)also ran the coolest
also was told that our local stuff was between 110 and 116 octaine depending on weather it was unleaded or leaded

kev

kev

premix will go bad in 30 days/if were me 86 fuel

later cdpcb

At this point I'm not willing to change. I've herd it all. The emperical results are this...I've spanked that Group K Type II mod for over 100 grunting hours and 3 years w/o a single problem.

Oh, yeah auto gas and av gas both weigh the same, about 6.2 lbs /gal.

great weedwacker fuel

Ask Fercho, I read somewhere he ran av/race fuel in his ski at the MB.. well thats what I read.

tj seriously you dumped 15 gallons of AV mixed fuel. I could use some of it for my Stihl Chainsaw, weedeater and my blender.

Mick

I thought there was a difference between race gas you buy at the track and AV gas - two totally different gasolines.

when i was racing you could not buy gas at the track
had to buy it from the local servo and it was av gas they sold not race fuel
our club used to sell vp fuels to whoever wanted race fuels
some other servo's(shell)used to sell raceing fuel A in 20 liter drums

kev

kev