The problem with Amsoil is that the carbon formed is very hard and brown. It is very difficult to remove. In the UAV community where engines are run for hours, Amsoil lubed engines fail much quicker than other oils. This is especially true of the 80-100:1 mix of saber. The hobby flyer never works his engine much and so they don't notice the wear from Amsoil 100:1.

I did an oil/engine run test a few years back and if people are interested, I can repost the pictures. It shows amsoil's problems. For all of my work planes, I use Pennzoil air cooled which tested out as one of the better oils

Elson