Winterizing Your Tohatsu Outboard

Outboard Winterizing Tips

To help keep your engine in tip-top condition for years to come, it is important that you“winterize” your outboard for off-season storage. By winterizing your outboard, you will help ensure that your outboard will be ready to go at the start of next year's boating season.

Winterizing Your Outboard

Step One

Thoroughly flush your engine with clean, fresh water.

All Tohatsu outboards are water cooled; running your outboard without an adequate source of cooling water will result in severe damage to your outboard!

Smaller Horsepower Outboard (2hp through 6hp):


For our 4-stroke models 2hp-6hp and our 5hp 2-stroke models you can use the optional flushing plug or attachment. For smaller outboards, you can also flush your outboard by using a large container (large bucket or garbage can) of water. Be sure the container is large enough to completely cover the water intake ports and the lower unit of the outboard. Also be sure that the container is wide enough so that no part of the motor will touch the sides/bottom of the bucket. Securely mount your outboard on a sawhorse or some other type of apparatus that will allow safe operation of your outboard.

8 hp and up:


With the 8-140 hp you can either use the optional flushing plug which can be attached to a hose for flushing the engine with fresh water or purchase a set of “ear muffs” (available at your local marine dealer). This equipment attaches to your garden hose and clamps on to your outboard's lower unit, covering the water intake ports. Turn the garden hose 1/2 to full before starting your engine to get a good water flow without too much pressure (to minimize air bubbles).




Run your outboard at normal idle speed for 5-10 minutes to allow the engine to warm up. It is best to use a mixture of stabilized fuel with fogging oil. (follow brand directions and be sure 2-stroke pre-mix models have the appropriate oil also in the fuel). Or, you may remove the air box and spray fogging oil through the carburetor/s throat(s) while running the engine just before you shut it down. This will cause excessive smoke and ensure that all internal parts are lubricated. If you plan to leave the stabilized fuel in the tank (for short seasonal periods-usually 3 months or less), then be sure it is full to keep evaporation and condensation to a minimum. Or you may drain the fuel system completely for longer periods (see Step 2). Fuel quality can be different in many areas. Check with your local Marina or Dealer to have your motor winterized, or see which procedure is best in your area.

After flushing the outboard, allow the water to completely drain from the engine (see Step 2 before you shut off your engine if you plan to "fog" your engine manually). Your outboard should be in a vertical position for the water to completely drain. While you're waiting for your engine to drain, wipe off any dirt, grease, etc. from the exterior of the engine.

Step Two

If fogging the motor manually, disconnect the fuel line at the motor and continue running the motor until it runs out of gas. It is extremely important to ensure that the fuel system is completely drained. If not completely drained, deposits (gum, varnish, etc.) may form inside the carburetor. 

To drain the fuel from the carburetor you can use one of these techniques:

As the fuel begins to run out and the motor starts to "die", choke the engine a little until the RPMs pick back up. Continue choking the engine as the engine starts to die out until the fuel supply is finally exhausted.



Remove the drain screw from the carburetor bowl and allow all fuel to drain out. Replace the screw when finished. Although this technique requires a bit more effort than the first, it is recommended to use this procedure to fully ensure that all fuel has been removed from the carburetor.


If you have fuel left in your tank, add Fuel Stabilizer to it and fill the tank to keep condensation and evaporation to a minimum.

For carbureted 2-stroke motors: If your outboard is not an oil-injected model (i.e. you mix your gas/oil manually), we highly recommend you do not store the gasoline for extended periods of time. Over time, the gas and oil will separate which will lead to a lack of lubrication to your engine.

Step Three

Treat your outboard with “storage oil” (also called “fogging oil”), unless treated or sprayed as in Step 1.

Storage oil comes in an aerosol spray can and is used to prevent rust on the engine's cylinder, crankshaft, bearings, pistons, etc. and can be purchased at most local marine dealers. Follow the oil manufacturer's recommendation on the amount of storage oil to use (generally about 2 ounces for each cylinder).

First, remove the spark plug(s) and the stop switch lanyard cord from your outboard. It is also a good idea to disconnect the spark plug wires from the spark plugs to prevent accidental starting.

Manual Start Outboards:


Slowly turn the engine over a few times using the pull cord while spraying the storage oil into the spark plug holes.

Electric Start Outboards:


Be sure you have water hooked up to your water intakes before turning over your outboard to prevent damage to your water pump. While spraying the storage oil into the spark plug holes, turn the engine over in 5 second bursts using your electric starter. Do not over “crank” your engine or you could damage the electric starter.


Step Four

Apply water resistant grease to propeller shaft. Using a wheel bearing grease (or something similar), thoroughly grease the prop shaft and prop shaft threads.

Step Five

Change the gear oil in the lower unit (step-by-step instructions).

For 4-Stroke models you should also change your crankcase oil to remove any acids and moisture from the oil.

Step Six

Apply water resistant grease to all moving parts, joints, bolts, nuts, and plastic fittings.

Step Seven

To help keep your factory finish looking new, apply a light coat of oil (or spray lube) to the exterior. Or you can also wax the exterior of your outboard using a high grade automobile wax.

Step Eight

Store the engine vertically in a dry area. If you store your boat in the water there are several schools of thoughts regarding whether you should store your engine in or out of the water. There are advantages and disadvantages of both ways and unfortunately there is no one “correct” or “best” way. Numerous factors such as temperature, salt/fresh water, algae growth, corrosion, etc. must be taken into account when deciding whether to leave your outboard in the water or tilt it up out of the water.

To find out which is “best” way we recommend you ask your local marina, fellow boaters in your area, etc. how they store their boat/outboard during the off-season.

Factors to keep in mind:


Storing in water allows algae and corrosion to affect your outboard.


Storing out of the water could cause damage if the outside temperature reaches freezing and there is water in your lower unit.


If you store your motor tilted up, we recommend you remove your prop to decrease the temptation of someone stealing your prop.


Storing down in the salt water drastically increases the potential for corrosion.



Battery Storage

Step One

Disconnect the battery cables and clean the battery terminals using a wire brush.

Step Two

Recharge the battery to full strength. You should also recharge the battery once a month during the off-season to prevent electrical discharge and degradation of the electrolytes.

Step Three

Clean the exterior of the battery.

Step Four

Apply grease (Vaseline works nicely) to the battery terminals.

Step Five

Store your battery in a dry place.

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