How To Winterise Your Jet Ski Properly: A Complete Step-By-Step Guide

29th Jul 2026

How To Winterise Your Jet Ski Properly: A Complete Step-By-Step Guide

Even if you live in Australia, there are times when your jet ski may sit unused for weeks or even months. Proper winterisation—or long-term storage preparation—is one of the best ways to protect your investment and ensure it's ready to hit the water when riding season returns.

Leaving fuel, saltwater and moisture inside your jet ski can lead to corrosion, flat batteries, stale fuel and expensive repairs.

Follow this simple guide to store your Sea-Doo, Yamaha or Kawasaki the right way.

Why Winterising Is Important

When a jet ski sits unused, several problems can develop:

  • Stale fuel

  • Corrosion inside the cooling system

  • Flat batteries

  • Internal engine corrosion

  • Seized bearings

  • Mould and mildew

  • Damaged seals and hoses

A couple of hours of preventative maintenance can save hundreds—or even thousands—of dollars in repair costs.

Step 1: Give Your Jet Ski A Thorough Wash

Start by washing the entire ski with fresh water.

Pay particular attention to:

  • Hull

  • Deck

  • Jet pump

  • Intake grate

  • Trailer

  • Engine bay (avoid directly spraying electrical components)

Removing salt and dirt now prevents corrosion while the ski is in storage.

Step 2: Flush The Cooling System

If you've been riding in saltwater, flushing is essential.

Follow the correct flushing sequence:

Start-Up

  1. Start the engine.

  2. Turn the water on.

  3. Flush for approximately 2–5 minutes.

Shut-Down

  1. Turn the water off.

  2. Allow the engine to idle for 10–15 seconds.

  3. Turn the engine off.

This helps remove salt deposits from the cooling system and exhaust.

Step 3: Stabilise The Fuel

Fuel begins to deteriorate surprisingly quickly.

Add a quality fuel stabiliser to the tank and run the engine briefly so the treated fuel circulates through the fuel system.

This helps prevent:

  • Gum deposits

  • Injector blockage

  • Fuel pump issues

  • Hard starting

If storing for an extended period, keeping the fuel tank nearly full also helps reduce condensation.

Step 4: Change The Engine Oil (Four-Stroke Models)

If your jet ski is due for an oil change, do it before storage.

Used engine oil contains contaminants that can cause corrosion while the engine sits unused.

Also replace the oil filter if it's due.

Step 5: Protect The Battery

Disconnect the battery or remove it completely if storing for several months.

The best option is to connect it to a quality maintenance charger.

Before reconnecting:

  • Clean battery terminals

  • Check for corrosion

  • Apply dielectric grease if required

A healthy battery makes the first start of the season much easier.

Step 6: Protect Against Corrosion

Saltwater riders should apply a corrosion inhibitor to exposed metal components.

Focus on:

  • Hose clamps

  • Electrical connectors

  • Linkages

  • Fasteners

  • Steering components

  • Engine exterior

Avoid spraying belts or clutch components.

Step 7: Inspect The Jet Pump

Before storage, inspect:

  • Impeller

  • Wear ring

  • Intake grate

  • Steering nozzle

  • Reverse bucket

Remove any fishing line or debris wrapped around the driveshaft.

Leaving debris in the pump can damage seals over time.

Step 8: Lubricate Moving Components

Apply marine-grade lubricant to:

  • Steering pivots

  • Reverse linkage

  • Control cables

  • Trailer winch

  • Trailer coupling

Keeping these components lubricated helps prevent corrosion and stiffness.

Step 9: Store It Correctly

Where possible, store your jet ski:

  • Under cover

  • Out of direct sunlight

  • On a level trailer

  • With a breathable cover

  • In a well-ventilated area

Avoid airtight plastic covers that trap moisture.

If storing outdoors, ensure the cover is secure and won't flap against the hull.

Step 10: Prepare For The Next Season

Before your first ride after storage:

  • Reconnect the battery

  • Check engine oil

  • Inspect coolant (closed-loop systems)

  • Check fuel

  • Test lights and gauges

  • Inspect hoses

  • Check steering operation

  • Examine the jet pump

  • Ensure the drain plugs are fitted

Taking a few minutes to inspect the ski can prevent unwanted surprises at the boat ramp.

Common Winter Storage Mistakes

Avoid these common errors:

  • Leaving saltwater inside the cooling system

  • Forgetting to stabilise fuel

  • Leaving a flat battery connected

  • Storing with a dirty hull

  • Ignoring corrosion

  • Covering the ski while it's still wet

  • Forgetting to inspect the jet pump

Winter Is The Perfect Time For Maintenance

Long-term storage is also an excellent opportunity to replace worn components before the next season.

Popular maintenance items include:

  • Spark plugs

  • Oil filters

  • Fuel filters

  • Batteries

  • Wear rings

  • Impellers

  • Starter motors

  • Starter solenoids

  • Bearings and seals

  • Service kits

Completing these jobs during the off-season means less downtime when the weather warms up.

Need Parts Before Next Season?

At Jet Ski Parts Warehouse, we stock thousands of genuine OEM, aftermarket and quality used parts for Sea-Doo, Yamaha and Kawasaki jet skis.

Whether you're performing a routine service, replacing worn components or carrying out a complete rebuild, our experienced team can help you find the right parts to get your ski ready for the next ride.

Final Thoughts

Proper winterisation is about more than just parking your jet ski in the shed. Cleaning, flushing, protecting the fuel system and preventing corrosion all play a vital role in keeping your PWC reliable and ready for the next adventure.

A little preparation today can save significant time, money and frustration when it's time to get back on the water.