I have used it @ 100:1 with my 3 cahinsaws and leaf weed trimmer. No problems. A mason down the road sais he been using it 12 years and never blew a motor. How can some use it 10, 15, 20 years and never have a problem, a few use it once and they blow the motor? Also, a 2 cycle @ 18,000 rpm's is sure extreme duty and was told to use 50: 1 ratio. Then he goes back to his old oil ( at 50:1 ) and has no problems. I think he answered his problem. Oh well , I will trust science. I have heard Amsoil tested Saber @ 300:1 and still didn't blow the motor. Actually sometimes I run my saw@ 128:1 but asked myself why do I do such dumb things? Sometimes I just keep it easy and put 2 oz. per gal. (64:1)