Absolutely nothing for 8 years straight except Stabil in the fuel tank. The Merc is self-draining and runs carbon-free on Regular fuel. No new filters, no new fluid, no new sparkplugs. But, hey, feel free to fork over 3 or 4 hundred bucks to your favorite dealer or mechanic every Fall if it makes you sleep better.
Except for flushing, I've run mine in Colorado and South Florida for 8 years straight and still run the original sparkplugs and sacrificial anodes. Unlike my girlfriend, this is an almost maintenance-free design.
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