I bought a sled a few years ago with a stuck engine. I was planning to tear it down and re-ring/rebuild as needed. I took the plugs out and poured some seafoam down each hole--with no expectations, just to try it, a few days later the motor freed on its own, had good compression, I cleaned the carbs and got it running. Ran great, no noise--put about 3000 miles on sled, good compression, still runs good. That made me a beliver, I use it in the spring for storage rather than stabil, on rare occaisions put a bottle in the car/truck (fuel) but never in oil. I use amsoil at 20,000 mile intervals and stays clean, car just turned 220k miles last week.