Tips on How To Winterize a Jet Ski

Jet skis offer hours of high-speed marine fun. With cold weather coming, learn how to winterize a jet ski properly.

Jet skis are great fun, and although I don’t own one (yet), I get on one every chance I get. Luckily for me, a good friend owns one and lets me take it for a spin from time to time during the summer.

Being practical-minded, I decided to pick my friend’s brain on how to winterize a jet ski so I’d know exactly what to do when I finally get one. Where I live in Canada, we get freezing temperatures at least five months a year, so winterizing jet skis and other outdoor machines is a big deal.

If you own a jet ski in a cold climate, winterizing your rig is a must. Fail to do so and you risk permanent damage. Follow the steps below to learn how to winterize a jet ski properly.


  • Jet ski trailer;
  • Portable water pump with two hose attachments;
  • Car washing sponge;
  • Large plastic bucket;
  • Hose and water source.


  • Fuel stabilizer;
  • Four gallons RV & marine antifreeze;
  • Silicone spray;
  • Engine fogging oil;
  • New spark plugs for your jet ski;
  • Anti-seize compound;
  • Mild dish soap;
  • Marine wax.

Stabilize Fuel

  • Plan a specific day to take your jet ski on the water for the last run of the season.
  • Top off the gas tank before heading out.
  • Add fuel stabilizer to the tank in the proper ratio (usually one ounce of stabilizer per two gallons of gas).
  • Take the jet ski on a short run to work the stabilized gas through the system.
  • Once it’s out of the water and on the trailer, top off the gas tank once more. Add stabilizer in the correct ratio if you burned a significant amount of gas.

Remove Excess Water From Exhaust System

  • Bring your jet ski to where you plan to store it for winter.
  • Ensure the drain port at the back of the jet ski is open, then run the engine for no more than five seconds. (Any longer when it’s out of the water will damage the engine.) Rev the engine a couple of times during this five-second period, then shut it off. This will drain any excess water from the exhaust system.

Add Antifreeze

  • Locate the threaded flush port at the rear of the jet ski if it’s a newer model, or the coolant intake hose in the engine compartment if it’s an older one.
  • Thread your two hose attachments to the inlet and outlet ports of your portable pump, then thread the other end of the outlet hose to the flush port of your jet ski. (If it lacks a flush port, disconnect the coolant intake line and temporarily replace it with the pump’s outlet hose.)
  • Empty the four one-gallon jugs of marine antifreeze into the large bucket, then slide the bucket directly under the jet ski’s rear exhaust port.
  • Submerge the pump intake hose into the bucket of antifreeze.
  • Start the engine, then immediately switch on the pump. Be sure not to start the pump before firing up the engine, or you’ll force antifreeze into parts of the engine where it shouldn’t be.
  • Let the jet ski and pump run for about 30 seconds. You should see pink antifreeze pouring out of the exhaust and falling into the bucket. Once this happens, shut off the pump first, then the jet ski.
  • Disconnect the pump from the jet ski, then use it to pump the antifreeze from the bucket back into the jugs it came in.

Remove and Inspect Spark Plugs

  • Locate and pull out the spark plugs from the engine.
  • Inspect for black carbon buildup or oily residue. Replace the plugs if necessary.
  • Spray a quick shot of engine fogging oil into the cylinders where the spark plugs were.
  • Brush a little anti-seize compound onto the spark plug threads, then replace them in the cylinders.

Protect Engine With Silicone Spray

  • Coat all the exposed metal parts of your engine with silicone spray.
  • Locate all exposed bolt heads and moving metal parts at the rear of the jet ski, where the pump and intelligent brake and reverse (IBR) system are housed.
  • Insert your key into the ignition, turn on the power to your jet ski without starting the engine, then use the IBR controls to raise it into the up position.
  • Coat all bolt heads and IBR parts with silicone spray.

Remove and Store Battery

  • Disconnect wires from battery terminals.
  • Remove battery and store it in a heated space to preserve battery life.

Clean and Wax Jet Ski

  • Inspect jet ski hull, removing any dirt or algae.
  • Wash the hull if necessary
  • Apply marine wax with a microfiber cloth.

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Robert Maxwell
Robert Maxwell is a writer, videographer, photographer and online strength coach based in Northern Ontario, Canada. He grew up on a rural self-sufficient homestead property where he learned the skills to build his own home from the ground up, do all his own vehicle repairs, and work with wood, stone and metal to find practical DIY solutions to many everyday problems.