Mercury - Power Tune Internal Engine Cleaner Engine Care Series Spray Formula 858080K03. Overview. There's a certain peace you feel when you fire up your engine and know it's breathing clean and strong. Anyone who spends real time on the water understands that confidence-it's not flashy, it's earned. Mercury Power Tune Internal Engine Cleaner is one of those quiet helpers that keeps things running the way they should. When you've got miles of open water ahead or you're easing back into the marin