How long does it sit between uses? I use a mix of Marine Stabil, Startron and Sea Foam ,all varying, depending on how I'm using a boat. If I am using it a lot it gets SeaFoam only. When I know its going to sit a few weeks ( yes not months just weeks) I add some marine stabil and startron as I feel both have different attributes. I know some 4 stroke guys who swear by adding a couple of ounces of Marvel Mystery oil to every tank of gas for the new injector issues. All the new gas is junk ethanol or not. It is designed to be used up quickly not stored. The additives that gave gas better storage properties have either been banned by epa or dropped/replaced to lower production costs and allow ethanol to blend better. My Seapro I sold had not been on the water in over 1.5yrs was stored outside with local ethanol gas in it, 1/2 tank, Startron, Stabil and Seafoam. added. I just knew I had made a huge mistake not dumping it sooner but took the chance. I fired it up on the muffs for about 30min, ran fine, took it to the river and ran the heck out of it down to less than 1/8 tank. Came home and dumped the filter in a clean bucket. Nothing but gas, no water no milky stuff. Added 10 gal fresh gas, 1/4 can of seafoam and went joyriding again. RPM improved over the old gas but boat still ran fine. New owner uses the heck out of it and has had no issues. Granted mine was a 2 stroke with oil inj and Carbs.