I write this letter a little late but still satisfied. This past summer I purchased two large V8 Microlon engine kits and two automatic transmission treatment kits. I read all about how this is a one-time engine treatment and figured I knew all about engines. Well I guess I have to admit after talking with you I forgot one simple thing. Boat engines run cooler than cars and trucks, the thermostats are set at 160 not 180 degrees. The net result is it took me 12 hours of running time before I saw any change. The change I saw now is running 300 rpm less and about 3 more miles per hour faster. I cruise at the same speeds as always but 300 rpm less, my gas was lasting longer and the boat was running smoother. I felt you needed to hear that you were right. If I was a little handier around engines I would have restricted the water flow and make the engines run warmer. Next boat I guess I will ask for some help. The boat treated was a 1999 37′ SeaRay Express. Thanks again for the great product.