i know it may sound funny but i notice a huge difference when i use high octane gas from texeco. it seems like my boat, and car for that matter, don't do nearly as well with anything else. i mentioned this to a mechanic and he told me you can buy much better gasfrom car stores like schuck's or napa and that the dfference would be unreal, only problem is it may cost 4 bucks a gallon. may be worth it to help clean out your system. who knows?