How To Winterize Your Jet Ski in 6 Simple Steps

The season is ending, and if it gets below 40°F/5°C where you live, you should winterize your jet ski.

I say 40F to give people some leeway, as far too many forget to do it or do it too late.

Why Winterize A Jet Ski?

You winterize a jet ski to protect it from the elements while it sits for long periods of time. You should especially do this if it gets below freezing where you live.

Jet skis take in water, even Sea-Doo’s with a closed loop system, and if you don’t get this water out it can freeze. When water freezes it expands, and it’s strong enough to break metal, like your engine block.

Winterizing is a normal maintenance item that most people should do.

How-To Winterize A Jet Ski

Supplies Needed

• 1-Gal per jet ski of RV & Marine Antifreeze*
• Large funnel*
• Flushing Adaptor for Yamaha*, Sea-Doo and Kawasaki use a short garden hose.
• Marine fuel stablizer*
• Multi-purpose lube spray* or silicone spray lubricant
• Fogging spray oil*
• Smart battery charger

Video Guide:

Here are the written steps to winterize your jet ski:

1. Add Fuel Stabilizer to Gas

You want to either fill your jet ski gas tank all the way up or a quarter tank full for winter storage.

No matter how much fuel, you need to add fuel stabilizer(Sta-Bil) at the correct amount.

Be sure to add it before flushing, so we know the fuel lines get the mixture too.

2. Flush With RV & Marine Antifreeze

You need to drain any water from the watercraft engine, exhaust or intercooler. You do this by flushing the watercraft with marine antifreeze. You could use compressed air, but I don’t find it as effective.

Pink or RV/Marine antifreeze is safe for the environment. It’s also safer on the rubber seals, that’s why we use it.

Important: You must have the engine on when flushing your jet ski with antifreeze. 

Flushing Steps

1. Level the machine.
2. Hook up the transfer pump to the flush port and get the antifreeze ready.
3. Turn the engine on.
4. Turn on the transfer pump and use the whole gallon of antifreeze.
5. When done with the antifreeze, turn the transfer pump off and then turn the engine off.

You want to see antifreeze come out the exhaust, pump or side discharge port of the jet ski. If you don’t see antifreeze come out of ONE of these ports after 20 seconds, turn the pump off and then the engine off, as something is not right.

Drill Pump

A drill pump* works great as a transfer pump, as shown in the video below.

3. Fog Your Engine

Since your watercraft will be sitting for a few months, it’s best to fog the engine.

To fog your engine requires you to remove the spark plugs and spray fogging oil into each cylinder for about 3 seconds.

With the throttle pulled in, hold the start button and turn the engine over a few times.

With the throttle held in, it keeps the engine from starting.

Some Waverunners need you to hold the start and stop button together instead of the throttle.

When the season starts again, consider replacing the spark plugs. Fogging oil can foul spark plugs.

4. Remove Your Battery And Keep It On Charge

In winter, keep your battery charged with a smart charger or use a solar charger if it’s outside.

Batteries die from inactivity

If you don’t keep your batteries on charge during the winter, you run the risk of them being dead next season. Lead-acid batteries go flat when they’re not used or kept on charge.

You can see our guide here to see what smart battery charger or solar charger you should get.

5. Rinse And Then Lubricate Everything

Take the seats off and unscrew the drain plugs.

Tilt the jet ski back, rinse the hull with a hose to remove saltwater and debris, and then allow it to dry.

Lubricate engine parts, seals, cables, and moving parts with anti-corrosion spray.

6. Put A Cover On

If you have an OEM cover, put that on, but also get another cover to go over that for winter storage.

Small critters like to sneak into your watercraft. They get in through exhaust port and other openings during the winter. Once inside, they like to eat wires and rubber hoses, which damages the machine. Throwing on a bigger second cover keeps them out.

Any general-purpose or universal fitting jet ski cover will do.

Shrink-wrapping the jet ski is even better, but more costly and one time use.

Clean Items Out

Before putting the cover on, it’s a good idea to clean the jet ski of any items in the storage compartments.

Also, consider cleaning the bottom of the hull to keep the scum from building up. It’s much harder to remove after it’s been drying for months after winterizing it.