When I bought my new boat with a 150 ETEC, I gave my old boat to my son. It is a ProGator Solution with a 115hp Johnson, both 1980. I always ran 91 octane, with Johnson Oil and 2+4 Fuel Conditioner. Always kept it maintained, and have never had a major issue with the motor. Still runs great and I don't even want to think about how many hours are on it. I bought a couple of cases of XD100 to use in the new ETEC. Would there be any issue in using the XD100 in the Johnson, still mixing 50:1? Based on what I have read, it should not be a problem, but I wanted to ask the experts. Thanks.....