test for autogas/avgas contamination?

Does anyone know how to determine if autogas is being used to 'cut' avgas?

If there were an appreciable amount of ethanol in the autogas and the avgas was adulterated with a large percentage of autogas, maybe the water extraction test would work(if only to demonstrate that there is ethanol present).

If autogas and avgas are mixed 50/50, will the mixture still be blue?

Maybe a simple test to determine the concentration of lead(as a way to determine if the avgas is being diluted with autogas)?

Any ideas?

Big problem

First, if you suspect someone in the chain of ownership of this fuel is cutting it with auto fuel, you should notify the oil company named on the pump. Someone will be getting into big trouble.

Two "quick" tests will give you some clue if this fuel is being "cut". The ethanol test you already mentioned, and a vapor pressure test. This can be done with a $50 vapor tester. http://www.decalinchemicals.com/fueltester.html

Of course you already know this, but if you have an engine that really requires avgas, and you don't trust the source of your fuel, I would strongly urge you to get it somewhere else!

All that said, I would be *very* surprised if someone is purposely contaminating avgas. The risk/reward ratio on that is very high.

I'm pretty sure the color of autofuel will discolor the avgas even if a small percentage is added. It will turn the avgas a dingy green color. I had autofuel in my 50 gallon fuel trailer for my SeaRey. When I drained it nearly dry (all but less than a gallon) and refilled it with 100LL for my RV-7A, it still turned it slightly green. We had "real gas" auto fuel with no ethanol so I wasn't too concerned.

Also, autofuel has those awful aromatics, so it is also easy to detect by smell. If the fuel does not smell right, it is corrupted in some way.

Roberta

thanks

Mickey and Roberta,
Thanks for the advice.
I haven't bought a gadget lately and that vapor pressure tester might be just the thing. And test mixing fuels to see what happens to the color is also an excellent idea(sometimes the obvious is easily overlooked).

I've been running a mixture of 100LL and autogas in my low compression IO-320-A2B for years. I usually mix it about 4:1 auto to avgas. The only color difference I've noted is that the mixture is slightly paler blue - much less so than you would expect based on the proportions. It still smells pretty much like avgas too.