I just got my 1st DA-100. I have been using AMSOIL in my DA-50's, I have the small packets that just say to mix 1 bag (1.5 oz) for each gallon of gas. How much should I mix for a 80 or 100:1 ratio of fuel to oil?

R/C Foolish

A packet containing 1.5 oz of oil will give you a mix of approx 85:1 per gallon. For a 80:1 ratio you need 1.6 oz and for 100:1 you need 1.28 oz of oil per gallon, which is much too little oil for my liking no matter how exotic the oil might be.

Too many persons much more knowledgable than me shy away from those high ratios and Amsoil in particular, and stay in the 32-50:1 ratio range, which is where I feel most comfortable.

Karol

1 packet (1.5 oz) of AMSOIL per gallon will be fine. It is what the manufacturer recommends.
Down here in the SW desert we run closer to 80 to 1 in the summer. After hundreds of flights my engine shows very little wear and the pistons and rings stay very clean.