How To Winterize & Prepare Jet Skis For Multi-Month Storage

As the chill of winter sets in, it’s a good time to start thinking about safeguarding your personal watercraft (PWC) or jet ski as some call it, against the biting cold and freezing conditions.

It’s important that you ensure your PWC and trailer are thoroughly prepared for the winter months for maintaining their performance and longevity!!!

In this guide, I’ll show you the steps to start the winterize process for a Sea-Doo jet ski and get it ready for long-term storage, along with bonus tips I’ve picked up over the years. Winterizing a Sea-Doo, or really any jet ski, is a super important process, especially if you live somewhere that gets below 40F/5C! You’ll be surprised to learn how many people simply forget to get their jet ski winterized, so don’t let it slip you by!

Note: This post is more geared towards Sea-Doo, but it’s pretty much the same for a Yamaha and Kawasaki jet ski.

What Supplies You’ll need:

You’ll need to purchase these items for multiple years of use.

1. 1-Gal (per machine) of RV/Marine Antifreeze.
2. Marine fuel and gas stabilizer.
3. Fogging spray storage oil.
4. WD-40 Silicone spray lubricant.

How To Winterize A Sea-Doo Jet Ski And Most Other PWCs

To winterize most models of jet ski correctly, you’ll add fuel stabilizer, flush it with antifreeze, fog the cylinders, remove the battery, and lubricate parts.

Below, I’ve listed the full steps you need to take for most jet skis:

1: Add Fuel Stabilizer

You must add a fuel stabilizer to the gas tank to keep the fuel in great shape as the PWC sits. The fuel stabilizer bottles generally include measurements suitable for a gas tank ranging from 5 to 20 gallons.

If you’re wondering about whether to keep the fuel tank full or nearly empty is up to you.

When it comes to winterizing, you want to add the fuel stabilizer first, ensuring it mixes well and reaches all the fuel lines before starting the next winterize steps.

2: Flush With Antifreeze

The most important step, in winterizing, involves removing the water from the PWC engine and exhaust system!

The way you remove water from the engine is by using a marine-grade antifreeze. Below, I’ve listed the steps to use for flushing a PWC engine with the antifreeze.

1. Level PWC.
2. Connect the drill pump to the PWC flush port and get the antifreeze ready.
3. Turn the PWC engine on.
4. Turn on the drill pump and use the entire gallon of antifreeze.
5. When you use up the whole gallon of antifreeze, turn off the drill pump, then switch off the engine.

You want antifreeze coming out the exhaust, nozzle, jet pump area, or the side discharge port. 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 not going to plan!!!

The owner’s manual suggests using compressed air for removing any water, but I prefer a marine antifreeze.

I find it easier for people to get the drill pump than get an air compressor.

Should you add water to the antifreeze? The Marine and RV antifreeze should come pre-diluted and ready. Additionally, water remains in the cooling system of your PWC, hence winterization, as it inevitably blends with water.

3: Coat & Fog Internal Engine Parts

The reason you want to fog the jet ski engine is so you cover internal metal components to prevent rusting during periods of inactivity.

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

At the start of the season, it’s advisable to replace all your jet ski’s spark plugs because of the effect of the fogging oil.

4: Remove Battery & Charging Suggestions

The reality is that PWC batteries go flat during winter storage, so it’s best we remove them and keep them in a dry and above freezing place when you winterize.

Ideally, connect your battery to a smart charger that manages charging automatically. Alternatively, you can charge the watercraft every other month.

Will your battery be dead if it doesn’t get charged over winter? Maybe. The biggest complaint at the start of the seasons I get from people is that their Sea-Doo won’t start, and it’s because of the battery. Sea-Doo batteries are small and don’t get used enough, leading to them die. A battery charger proves effective in maintaining battery freshness throughout the winter season. The way I do is that I use a solar charger as I keep my Sea-Doo outside and get 5 years out of my batteries.

The solar charger doesn’t need direct sunlight and will keep jet ski batteries active and happy! It’s so stupid easy and effective that I don’t know why the manufacturers don’t just give them to people, or build them into the covers?

5: Spray WD40 specialist Silicone Lubricant

You’ll want to spray WD40 silicone spray lubricant on all metal and electrical parts, including the engine and pump area.

Let it sit for 15 minutes so it can air out, it’s flammable!!!

Make sure to lubricate the throttle and steering cables with marine grease.

Avoid regular WD-40, use the silicone version. The regular stuff doesn’t coat, it merely displaces water.

Here’s a useful tip for those residing near saltwater: regularly apply silicone spray on engine and jet pump areas. Repeat this process annually, allowing it to air dry for 15 minutes each time, and your jet ski will maintain its appearance for years!

6: Put Cover On

I suggest you take out the front storage accessories so you can prevent mold growth during storage.

A cover is ideal to keep debris off, for guarding against rodents, spiders, dust, and when outdoors, snow, sun, rain, and more. PWCs are magnets for critters, plenty of hiding places, and they think the rubber parts taste good.

Please consider getting a shrink wrapping job done to your PWC. Shrinking wrapping keeps the PWC in a perfect condition; snow and rain won’t affect it.

How To De-Winterize A Sea-Doo Jet Ski

To remove the winterize process from a Sea-Doo jet ski is super simple. Often, it only requires you to hook up the battery, put some fresh gas in, and take it for a ride.

But note, once the jet ski is started in water, it’s de-winterized and needs to be winterized again if you want to store it once more. I do suggest replacing the spark plugs as they can get fouled in the fogging steps.

To learn more, see my post here.

Trailer Care Tips

Regular PWC trailer maintenance is essential for prolonging the lifespan of your trailer.

Here’s what I suggest doing:

1. Lubricate wheel bearings.
2. Lubricate latch.
3. Ensure correct air pressure in tires.
4. Try to give a attempt to lift the tires off the ground when sitting for extended periods. Place blocks under the axle. Detach the tire to discourage theft of trailer.
5. Inspect straps, substituting any that show wear or fading.
6. Apply a anti-corrosion spray to trailer.

If you’re keeping your PWC on the trailer, consider tilting the trailer back by placing something under its nose. This action lets any stagnant water flow out from footwells or hull, preventing bugs and animals.

Winter Storage

Keeping your PWC in the water for a few days is fine, but any longer and you need a proper solution. Leaving them in the water for too long can damage it or worse, it can sink.

You have several options for long-term storage:

1. Trailer
2. Lift
3. Marina

The options mentioned above are common. Many trailer owners choose to store their PWC on a trailer itself, which is effective. Although some trailer maintenance, as detailed in this post, is required, this method often proves it’s a a cost-effective option for many.

For lakefront residents, I recommend investing in PWC lifts. The options include lifts for driving onto or lifts that elevate your PWC to a loading spot. Try figuring out what’s the perfect lift for your needs, I have a post that covers that here.

An alternative involves docking at the marina. The marina handles both launching and retrieving your jet ski, or provides a slip for your convenience.

Either option you go with, I suggest you put a cover on your PWC. Or, if you can, keep it in doors.

Security Protection

When your PWC will be inactive for an extended period, consider the risk of theft. How do you keep thieves away, let’s cover that point?

It’s important to understand that jet skis are highly sought after by thieves, particularly because they often contain an significant amount of fuel and their compact size makes them easy targets for quick thefts.

When you store your jet skis on a trailer, using trailer locks becomes vital. Making your machine harder to steal discourages potential thieves from targeting your stuff.

While situated on lifts, ensure the security of your jet skis by using chains or cable lock to attach the bow hook to the lift or dock.

For more information on security, read my post here.