I've found this very interesting about Amsoil. I have been running Amsoil in my ZDZ80RV since last October. I have about 50 flights since switching from Klotz KL-300 to Amsoil 2000.

Here are a couple of photos that I took through the spark plug hole. Kinda tricky to get focused. The piston is not coated evenly with the carbon material. Being careful not to disturb the material, I picked up a small piece with a small wooden stick. It is very soft and easily disintegrates between thumb and finger. Apparently, the material sloughs off during flying as shown by the bright shinny places on the piston.

I am running 93 octane gasoline at a 50:1 mix. The engine has very good compression. The spark plug had the medium tan color. ZDZ says to run synthetic at 40:1 so this rules out the option of going to the other Amsoil at 80:1 or 100:1.

Could the brand of gasoline cause the carbon build up?

I know this is a loaded question but if I should change to another synthetic at 40:1 then what would be my best choice?

Ken