How do you winterize a four stroke outboard?

Answer 1

NOTE: EFI/DFI engines should not be run out of gas due to damage to High Speed Fuel Pump for EFI in Vapor Separator - you "pickle" the fuel system. Also EFI and DFI engines should not be "fogged" through the throttle body as no fuel ever goes through the throttle body to flush excess oil, and oil can harm sensors. You fog the cylinders through the spark plug holes only, and use Outboard oil as fogging oil in the fuel to fog internal parts.

Suggested Process:

FUEL TREATMENT: Get a 3 gal marine gas tank you can use from year to year - fill it with 1 gal gas, add 8oz 2 stroke outboard oil, and one ounce of [ethanol fuel] Starbrite's StarTron fuel treatment [or similar ethanol approved fuel treatment]. Clean your fuel filter and drain it, Next, run this mixture through your running engine for ten minutes with fresh water supply to intake. {need lake or tub or motor flusher, fuel treatment, o/b oil, small fuel tank}

OIL CHANGE: Drain engine oil and change oil filter. Refill with fresh oil (many OEM suggest Synthetic Oil to prevent sludging) Rerun motor to distribute oil, then shut off, wait two minutes and check engine oil level. Now you are ready to remove from water (hose). {Need engine oil & filter, filter wrench, drain pan, drain screw wrench}

ANGLE/POSITION: Leave engine straight up and down so gearcase can drain water and exhaust housing cannot pocket water overwinter.

FOGGING FROM DEW CORROSION: Remove the spark plugs and spray 1 ounce of storage fogging oil into the cylinders. Replace the spark plugs, remove the safety lanyard to prevent starting, and crank the engine over a few revolutions to distribute the oil around the cylinders and valves. This will also spin the water impeller, so it dislodge pocketed water between the blades and gravity drain the water trapped in the water inlet line. {spark plug wrench, fogging oil}

GEARCASE: Next, drain and refill your gearlube (two screws are removed to drain. You refill from bottom hole to push new oil out of top hole. {gearlube, gearlube pump, drain pan}

GREASING: You have several grease zerks on the engine to lubricate, as well as the steering cable where it enters the motor bracket. {grease gun, wrenches to remove steering cable nut}

BATTERY: Disconnect battery, as a slow draw over winter will cause battery to discharge and once it reaches 25% charge (12v not 13.6v) it can freeze.

Keywords: Mercury Marine 25 hp-30-40-50-60-75-90-115-125-135-150-175-200-225-250-275-300 Outboard Motor Winterization technique