Actually I ended up taking the tank apart and the Aerotrend was pretty stiff. Not like a stick but more than I would like after one season. It's Neoprene inside the tank from now on. I'll use up my other 4 packs of Aerotrend outside the tank.

This gets a little more interesting. If you recall in post #18 I uploaded a photo of a rock hard stiff Aerotrend clunk line. It was out of a tank that uses an 80:1 Amsoil mix. I just inspected and changed out a clunk line in a tank that uses a 40:1 mix of Mobil 2T racing. Both were changed out last year( around mid Spring) at the same time and flown many times each this past season. The Aerotrend that came out of the 40:1 Mobile 2T tanks is about as soft and flexible as new unused Aerotrend Easy Flex I have on hand. I will say that the plane with the 80:1 Amsoil was flown a bit more than the other but the 40:1 Mobil was flown plenty of times this past season. The only thing I can think of is either the higher content of oil or the differences in additives or lack of between brands is keeping the tubing flexible in the 40:1 tank. What do you think??[sm=confused.gif] Here is a photo of the still supple Aerotrend out of the 40:1 Mobil 2T mix tank.

I would say VERY interesting. How about this: Put one chunk of the Aerotrend in a jar of the Amsoil/gas, one in a jar of the Mobil/gas, and one in a jar with the same gas but no oil. Pull them out periodically and compare. It wouldn't be a lot of work, and the results could be interesting. Here's another interesting fact: The spec sheet for Tygon 4040A states the tests for compatibility with gasoline are conducted with gasoline containing no alcohol. If I can find a station selling gas with ethanol in it I'll run that comparison.

Both of these mixes were using Amoco hi test with ethanol (up to 10% as stated on the pump). Makes me wonder if the more oil/ different additive/brand theory could also preserve the integrity/longevity of seals, gaskets and diaphrams etc. after extended use. I know when the skin on my elbows gets dry and brittle, I apply a little extra Nivea lotion (with aloe) to them to keep em' nice and moist and wrinkle free!