I have used Opti 2 for nearly 10 years in all my 2 stroke engines. The use primarily is with vintage Husqvarna motorcycles and a 1983 Husqvarna chainsaw as well. The bikes are 30 to 40 years old and once rebuilt are only fed this premix. Racing 1 for 10 plus years on the same rebuild with Optimol 2 and the bike preforms great. Excellent product that keeps old things young!!