Boating 101: Winterize Your Outboard Motor

By Capt. Vincent Daniello.

Boat yards winterize lots of boats in just a few weeks, so for tips to quickly store outboard engines, we went to Thurston’s Marina ( on Lake Winnipesaukee where they prep 150 outboards each fall against New Hampshire’s brutal winters.

1) To start, add fuel stabilizer, top off tanks, and run the engine in fresh water for about 10 minutes. “With the green STA-BIL, it’s easy to see when the additive makes it through all the fuel lines to the fuel filter,” says Assistant Service Manager Nicholas Thurston.

2) Thurston then connects a 3-gallon tank directly to the motor with his winter storage blend — 50 percent gasoline with fuel stabilizer, 40 percent fogging oil plus a bit of 2-stroke oil and gas-line antifreeze — that protects the fuel system and fogs the motor in 5 minutes running time.

3) If he uses traditional fogging oil rather than his storage blend, on a four-stroke outboard Thurston disconnects the hose that carries oily air from atop the cylinder head back to the engine air intake so he can spray fogging oil into the Positive Crankcase Ventilation valve.