Winterizing Outboard Motor

Winterizing Outboard Motor

As the leaves begin to turn and the chorus of migrating waterfowl looms ever closer, thoughts turn from lakes and rivers to fields and woods. Before putting the boat away for the season, however, proper winterizing will ensure your rig is ready to go in the spring. There are three general areas that require attention, including the outboard motor and fuel system, boat, and trailer.

Outboard Motor & Fuel System

  • Fill the fuel tank(s) with non-oxygenated fuel and add the proper amount of fuel stabilizer to the gasoline. The stabilizer will prevent fuel decomposition and varnish from building up in the fuel system. Full fuel tanks prevent condensation from forming on the inside of the tanks. In addition, full fuel tanks pose less potential fire risk than tanks that are only partially full.
  • Start the motor and let it run for 15-20 minutes to ensure that the stabilized fuel has been distributed to all points in the system, including fuel lines, filters, carburetors, etc. This can be done in the driveway, using a set of muffs and a garden hose to supply water to the intakes, or during the last outing of the season.
  • While the motor is still running, fog the motor by spraying fogging oil into the air intakes on the carburetors or the EFI system. It may be necessary to remove the air box to access the carburetor throats. Some motors are equipped with fogging ports that make the fogging process much easier. The fogging oil puts a liberal coating of oil on the internal motor components and prevents corrosion. Refer to your owners manual for specific instructions on how to fog your particular motor. The motor will smoke profusely and want to stall while the fogging oil is being injected. A little extra throttle will ensure that the motor remains running until the fogging process is complete. Once complete, allow the motor to stall by continuing to inject the fogging oil. Depending upon the particular motor, it may be easier to perform the fogging by using multiple cans of fogging oil at the same time.
  • With the kill switch in the “off” position, turn the motor over a few seconds to remove any residual water from the water pump.
  • Remove the spark plugs and spray fogging oil directly into each cylinder for 3-4 seconds while turning the motor over by hand. This will distribute a light coat of oil onto the cylinder walls.
  • Replace the spark plugs and torque to proper specifications. Install new spark plugs after the first run in the spring to ensure the new plugs do not become fouled with fogging oil.
  • Drain and refill the lower unit lubricant. Replace the washers on all drain and vent plugs each time the lower unit is serviced. Inspect the drained oil for any signs of water intrusion or chunks of metal on the drain screw magnet. If gearcase work is needed, the time to address the problem is now, not in the spring. It is best to allow the motor to sit for a day or so after use to allow any air entrained in the lubricant to escape prior to servicing the lower unit. The entrained air gives the lower unit lubricant a “milky” appearance, that is often confused with water in the lubricant.
  • Check the oil reservoir(s) for sludge (a turkey baster works well) and fill the oil reservoir with fresh oil to prevent condensation during storage. If you own a 4 stroke motor, change the crankcase oil and filter at this time.
  • If the motor is equipped with power tilt and trim, check the fluid level in the pump and top off if necessary. Refer to your owners manual for specific instructions on how to check the pump fluid level. Apply a film of grease to the tilt/trim rams to prevent corrosion and pitting.
  • Remove propeller and check for fishing line or other foreign material around the prop shaft near the seals. Inspect the prop for any nicks or cracks. Again, now is the time to address these types of problems. Before replacing the prop, wipe the old grease from the shaft and apply new lubricant. Finally, replace the prop, thrust washers, etc, and torque to proper specification.
  • Lubricate all service points, including grease zerks, shift and throttle linkages, etc. Refer to your owners manual for specific lubrication points.
  • Finally, store motor in the “down” position. This will ensure all water is completely drained, and prevents water from collecting in the exhaust and prop area. Also, with the motor in the lowest position, the tilt/trim rams (if equipped) are retracted within the pump housing, preventing surface corrosion on metal that would otherwise be exposed.


  • Remove all electronics and store in a warm, dry area. Most electronic items come with a plastic carrying case. These cases make ideal storage containers and protect the electronics from damage.
  • Trolling motors should be removed and stored in a heated area. The powerful magnets in today’s trolling motors can be damaged by freezing temperatures.
  • Remove all equipment and gear from the boat, including rods and tackle, anchors, ropes, etc. Check over all items for signs of wear or other defects, and repair or replace as necessary.
  • Check the water level in all batteries and bring all batteries up to a full state of charge. Clean and grease all battery connections to prevent corrosion. Ensure all switches are off or, better yet, disconnect all connections to the batteries. Cable ties can be used to keep all appropriate terminals together to ensure proper reconnection in the spring. If your boat is equipped with an appropriate on-board charging system, this can be left connected and on for the duration of storage. If not, check the batteries every couple of months, topping off the charge on each battery as necessary.
  • Check the boat’s steering and electrical systems for problems or wear. Clean and lube the steering rams if equipped with mechanical steering. Hydraulic systems should be topped off and marine grease applied to the cylinder ram to prevent corrosion and pitting.
  • Vacuum the floor and all compartments to remove any spilled foodstuffs that could attract mice or other rodents. Fabric softener sheets, such as Bounce, placed in all storage compartments and around the floor of the boat is an effective method of repelling rodents.
  • Prop all storage compartments open slightly with a piece of styrofoam or something similar to ensure that air can circulate throughout the entire boat. In addition, containers of moisture absorber such as Sta-dri, available from most hardware stores, can be placed in the boat to absorb moisture and prevent mildew.
  • If your boat utilizes removable pedestals, such as the Springfield Taper-Lock or Swivl-Eze Wedge systems, apply a light coating of lubricant, such as Paraffin wax, to the plastic portion that fits into the seat base. This will allow for easy removal of the pedestals in the future.
  • Check all livewells, pumps, and hoses to be sure all water is removed from the system. This can be accomplished easily with the use of an air compressor. Another option is to flush the entire system with RV antifreeze.
  • If your boat is equipped with a speedometer and/or water pressure gauge, ensure all water is removed from the lines. Any remaining water can freeze and crack the lines.
  • Check and tighten all screws throughout the boat.
  • If the boat will be stored outdoors, remove the drain plug and store the boat with the bow elevated. This will allow any water that should enter the boat to be able to drain.

If the boat will be stored outdoors, place a plastic tarp over the boat cover, if equipped. This will keep stains from birds, leaves, etc. off the cover, and will allow for easy snow removal. Make sure the cover and/or tarp is supported so that water and snow cannot collect and pool.


  • Remove, clean, and inspect the wheel bearings for signs of rust, pitting, etc. If the bearings are to be replaced, the bearings and races should be replaced as a set. The seals should be replaced each time the bearings are removed for inspection or replacement.
  • Rotate tires and check for proper inflation. This is typically 50 psi for trailer tires. Consult the sidewall of the tire for proper inflation pressure.
  • Inspect the trailer coupler and latch assembly. Replace worn or missing parts as needed.
  • Inspect the condition of the safety chains and all associated fasteners. Replace worn or missing parts as needed.
  • Check the operation/condition of all lights and wiring. Repair or replace as needed.
    � Inspect the winch strap, and replace if worn or torn.
  • Inspect all rollers/bunks, nuts, bolts and other hardware. Tighten or replace as necessary.
  • If the trailer is equipped with brakes, check the brake fluid level in the reservoir (if surge brakes). Also, check the condition of the pads and drums/rotors. Replace as needed.
  • Check the license plate for expiration dates, and renew as required.
  • If the boat will not have to be moved during storage, jack stands can be placed under the axles to remove the load from the bearings and tires.
  • If the boat will be stored outside, place a shield over the tires to protect them from the damaging UV rays of the sun, that deteriorates rubber compounds over time.By following these procedures along with specific items in your owners manual, you will be rewarded with a dependable outboard motor. A few dollars in materials and a few hours of your time will not only give you piece of mind about your investment, but can save on major repairs and major headaches come springtime.
  • Order Your Kit Here