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 skis, against the biting cold and freezing conditions.

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

Winterizing any boat is a super important process, especially if you live somewhere that gets below 40F/5C! You’ll be surprised by the number of people who simply forget about winterizing their jet ski, 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 Yamaha and Kawasaki jet skis.

What Supplies You’ll need:

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

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

How To Winterize Your Jet Ski

To winterize your jet ski, you must add fuel stabilizer, flush it with antifreeze, fog the cylinders, remove the battery, and lubricate a few parts.

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

1: Add Fuel Stabilizer

The first thing you must do is add fuel stabilizer to the gas tank to keep the fuel in great shape as the jet skis sits. The fuel stabilizer bottles generally include measurements suitable for a gas tank ranging from 2.5 to 20 gallons.

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

You want to add the fuel stabilizer first, ensuring it mixes well and reaches all the fuel lines, before starting the next steps.

2: Flush With Antifreeze

The second winterize step is the most important step, it involves removing the water from the 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 jet ski 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 jet ski 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 ski 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 when it comes to winterize process.

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 a winterize process, as it inevitably blends with water. So, adding more water is not what we want.

3: Coat & Fog Internal Engine Parts

The third step in how to winterize involves the engine and fogging it.

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

To fog a jet skis engine requires you to remove all spark plugs and spray fogging oil into each cylinder for about 3 seconds. The video below does a great job of showing this.

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

4: Remove Battery And Charge It

The reality is that ski batteries go flat during winter storage, so it’s best we remove them and keep them in a dry and above freezing, or we run the risk of a machine that won’t start.

Ideally, connect a battery to a smart charger that manages charging automatically. Alternatively, you can charge the ski 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 jet ski won’t start, and it’s because of the battery. PWC batteries are small and don’t get used enough, leading to them dying. A battery charger proves effective in maintaining battery life throughout the winter season. What I do is use a solar charger as I keep my jet skis outside and get 5 years out of my batteries.

The solar charger doesn’t need direct sunlight and will keep PWC batteries active and happy! It’s so stupid easy and effective that I don’t know why the jet skis manufacturers don’t just have the solar panels already on the covers?

5: Spray WD40 specialist Silicone Lubricant

When you winterize, 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 PWC will maintain its appearance for years!

6: Put The Jet Ski Cover On

Do not leave the cover off your PWC after you’ve winterized it, this is a very important step. The jet ski cover keeps the snow and more importantly, rodents, spiders and other critters from getting in and eating or destroying your PWC.

Rodents like the taste of rubber and plastic, so put a cover on your cover, if you ask me.

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

How To De-Winterize A PWC

If your PWC has been winterized, it’ll need to be de-winterized / summerized. The good news is that the de-winterize process is a lot easier than the winterize process.

1. Charge your battery.
2. Replace spark plugs.
3. Top up the gas tank with fresh gas.
4. Go for a ride.

Note: If you take your jet skis out for a winter ride, it will need to be winterized again as soon as it’s started in water it’s been de-winterized.

To learn more about this process, see my post here.

Trailer Care Tips

Regular jet ski 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 a 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 jet skis on the trailer, consider tilting the trailer back by placing something under the trailer “nose”. This action lets any stagnant water flow out from footwells or hull, preventing bugs and animals from making homes.

Winter Storage

Keeping your jet skis in fresh water for a few days is fine, but any longer and you need a proper solution. Saltwater, it’s best to take it out after you’re done for the day. 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 jet ski 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 cost-effective option for many.

For a lakefront resident, 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 skis, 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

One important step in how I winterize any vehicle of mine is giving it some security protection. PWCs are expensive, and security cameras are cheap these days, so why not have one watching your jet skis?

It’s important to understand that PWCs are highly sought after by thieves, particularly because they often contain a 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 PWCs by using chains or cable lock to attach the bow hook to the lift or dock.

I don’t stop there, look into Apple AirTags and hide it in the craft like I do. These things are cheap and simply work.

For more information on security, read my post here.