Winterizing Your Jet Skis and Other Personal Watercraft: The Complete Guide

When the last warm weekend of the season is behind you, it is tempting to park your jet ski in the garage and forget about it until spring. That shortcut can cost you. Water left in the hull, stale fuel, and a battery sitting at low charge for months are among the most common causes of cracked components, hard starts, and expensive repairs.

Winterizing your personal watercraft (PWC) protects your engine, fuel system, electrical components, and hull. It also makes spring start-up faster and cheaper. This guide covers every step, from flushing the engine to choosing the right storage spot, so your Sea-Doo, Yamaha WaveRunner, or Kawasaki Jet Ski is ready to ride when the weather turns.

Why Winterizing Your PWC Matters

Jet skis are built to handle water, but they are not built to sit idle for months in the cold. Winterizing matters for a few key reasons.

Freeze Damage Can Crack Expensive Parts

Any water left in the cooling system, exhaust, or hull can freeze and expand. That expansion can crack engine blocks, exhaust components, and hoses. Even in milder climates, a single hard freeze can cause damage that costs far more than the winterizing supplies would have.

Fuel Breaks Down Over Time

Gasoline begins to degrade within a few weeks. Ethanol-blended fuel absorbs moisture and can leave gummy deposits in carburetors, fuel injectors, and fuel lines. Treating your fuel before storage keeps those components clean and working.

Corrosion Starts Quietly

Salt, minerals, and moisture left inside the engine and pump will corrode metal surfaces during storage. A proper winterizing routine removes those contaminants and coats internal parts with protection.

What You Will Need Before You Start

Gathering supplies first makes the job go smoothly. Most owners need the following:

• A garden hose and a flush kit that fits your model
• Marine-grade fuel stabilizer and fogging oil from our PWC chemicals selection
• Fresh engine oil and a new filter for four-stroke models (browse oil filters and service kits)
• A set of spark plugs if yours are due for replacement
• Marine grease for fittings and cables
• A battery tender or charger
• Non-toxic marine antifreeze, if your owner's manual calls for it
• A breathable PWC cover and a PWC stand if you plan to store the craft off the trailer

Always keep your owner's manual nearby. Procedures vary between Sea-Doo, Yamaha, and Kawasaki models, and your manual is the final authority on your specific machine.

Step by Step: How to Winterize a Jet Ski

Step 1: Flush the Engine and Cooling System

Start with a thorough freshwater flush, especially if you ride in salt, brackish, or mineral-heavy water. Connect your hose to the flush port, start the engine, and run it according to your manual until the water runs clear. Salt left behind will crystallize and corrode internal passages over the winter.

If you do not already own one, a model-specific flush kit makes this step quick and repeatable. We carry flush kits for Kawasaki, Sea-Doo, and Yamaha watercraft.

Step 2: Stabilize the Fuel System

Fill the fuel tank close to full. A full tank leaves little room for air, which reduces condensation and moisture buildup. Add fuel stabilizer according to the product directions, then run the engine for about ten minutes so the treated fuel reaches the fuel rail, injectors, or carburetor.

If your watercraft uses a carburetor and has struggled with rough idling, consider a rebuild during the off season. Our carburetor rebuild kits are available for Kawasaki, Sea-Doo, and Yamaha models. Replacing an aging fuel filter now also helps prevent clogs in spring.

Step 3: Fog the Engine

Fogging oil coats the cylinder walls, pistons, and other internal parts with a protective film that blocks rust. Many owners remove the spark plugs, spray fogging oil into each cylinder, and briefly turn the engine over to spread it. Some models also allow fogging through the air intake while the engine runs. Check your manual for the approved method for your engine type.

While the plugs are out, inspect them. Worn or fouled plugs are a good reason to install fresh ones before spring.

Step 4: Change the Oil and Filter

On four-stroke models, used oil contains acids and contaminants that can damage engine parts during long storage. Change the oil and filter before putting the craft away so clean oil protects the engine all winter. Two-stroke owners should check and top off the oil injection reservoir and inspect lines for leaks.

Step 5: Drain Water from the Hull and Exhaust

Remove the drain plugs and tilt or raise the bow slightly, following your manual, so any water in the hull and exhaust system can escape. Open the engine compartment and sponge out any remaining moisture. Trapped water is the single biggest freeze risk, so take your time on this step.

Step 6: Protect the Cooling System in Freezing Climates

If your watercraft will sit in temperatures below freezing, many manufacturers recommend circulating non-toxic marine antifreeze through the cooling system after draining. Use only antifreeze approved for marine engines, and follow the exact procedure for your model. Never use automotive antifreeze unless your manual specifically allows it.

Step 7: Care for the Battery and Electrical System

Disconnect the battery, remove it, and clean the terminals. Store it in a cool, dry place and connect it to a battery tender every month or so. A battery left to drain completely in the cold can be permanently damaged.

Spray electrical connectors with a marine-grade corrosion inhibitor. If you noticed charging problems or dim gauges last season, winter is the ideal time to test and replace a stator, regulator rectifier, or starter.

Step 8: Inspect and Lubricate the Jet Pump and Steering

Look over the jet pump, impeller, and wear ring for nicks, dents, or excessive clearance. Damaged impellers reduce thrust and can strain the engine. If you find wear, an impeller and wear ring kit gets you back to peak performance. For pumps with bearing noise or leaking seals, a jet pump rebuild kit is worth considering.

Grease the steering and throttle linkages, and check cables for stiffness or fraying. Winter is the perfect time to swap out worn steering or throttle cables.

Step 9: Clean and Protect the Hull

Wash the exterior with a marine-safe cleaner, then apply a quality wax or protectant to the hull and seat. Inspect for cracks, loose trim, or damaged panels. If you spot damage, our hull and body parts section can help you find replacements before the new season begins.

Choosing the Right Storage Location

Where you store your PWC matters almost as much as how you prepare it.

Indoor Storage

A garage, barn, or storage unit is ideal. Indoor storage protects against ice, snow, UV exposure, and temperature swings. If possible, choose a spot with stable temperatures and good airflow.

Outdoor Storage

If you must store outdoors, use a heavy-duty, breathable cover that fits snugly and is secured against wind. Avoid plastic tarps that trap moisture and encourage mold. Park on a level surface and keep the craft off bare ground when possible.

Trailer or Stand

Storing the watercraft on its trailer works well for many owners, but take weight off the tires with jack stands to prevent flat spots. A dedicated PWC stand is another great option and keeps the hull supported evenly.

Keep Pests Out

Mice and other rodents love to nest in engine compartments. Place rodent deterrents in the storage area, plug exhaust and intake openings only if your manual advises it, and leave a visible reminder to remove anything you install before your first ride.

Winterizing Other Personal Watercraft and Marine Equipment

The same principles apply across other watercraft. Sit-down, stand-up, and three-seat models all need fuel stabilization, freeze protection, and a clean, dry hull. If you also own a boat or outboard, our marine parts section covers engine, fuel system, and electrical components for popular brands. Winterizing multiple machines in one weekend saves time and keeps your entire fleet protected.

Common Winterizing Mistakes to Avoid

Even experienced riders slip up. Watch out for these frequent errors:

• Skipping the freshwater flush after saltwater use
• Leaving the fuel tank nearly empty
• Using fuel stabilizer that is not rated for ethanol-blended gasoline
• Forgetting to drain water from the hull or exhaust
• Storing a battery on a cold concrete floor without charging it
• Covering the craft with a non-breathable tarp
• Ignoring owner's manual instructions specific to your model

Spring Start-Up Tips

Your winterizing work pays off when the weather warms. Before your first ride, reinstall the battery, check fluid levels, inspect hoses and clamps, and confirm that drain plugs are installed. Replace the lanyard if it looks worn (see our lanyards), and test the throttle and steering before launching. A quick pre-ride inspection helps ensure that your first outing of the season is trouble-free.

Get What You Need for a Smooth Off Season

Whether you need a flush kit, maintenance supplies, or replacement parts for a winter project, Bay Area Power Sports has you covered. Browse our full PWC parts and accessories catalog, and enjoy free shipping on all U.S. orders. Have questions about which parts fit your watercraft? Contact our team, and we will help you find the right match. For more maintenance tips, visit our blog.

FAQs About Winterizing Jet Skis

When should I winterize my jet ski?

Winterize before temperatures consistently drop near freezing, or whenever you plan to store the craft for more than a month. Most riders winterize in late fall, right after their final outing of the season.

Can I winterize a jet ski myself?

Yes. Most owners with basic tools and the owner's manual can complete the process in a few hours. If you are not comfortable with fogging, antifreeze circulation, or oil changes, a qualified marine technician can handle those steps.

Do I need to winterize my PWC if I live in a warm climate?

Not always for freeze protection, but stabilizing fuel, flushing the engine, and charging the battery still help. Any machine that sits unused for several weeks benefits from basic storage prep.

Should I store my jet ski with a full or empty fuel tank?

A nearly full tank is best. It reduces air space and condensation, and treated fuel is protected from breakdown. Always add stabilizer and run the engine so it circulates through the system.

What is fogging oil, and is it necessary?

Fogging oil is a protective spray that coats internal engine surfaces to prevent rust and corrosion during storage. It is strongly recommended for most two-stroke and many four-stroke engines, though your manual will specify the correct method.

Do I need antifreeze in my jet ski?

If your storage area drops below freezing and any water remains in the cooling system, marine antifreeze is often recommended. Use only non-toxic marine formulas approved for your engine, and follow your manufacturer's instructions.

How should I store my jet ski battery over winter?

Remove it, clean the terminals, and keep it in a cool, dry location. Connect it to a smart charger or battery tender periodically so it stays charged. Avoid leaving it fully discharged for long periods.

Is it okay to leave my PWC on its trailer all winter?

Yes, provided the tires are protected from flat spotting and the craft is covered or stored indoors. Many owners lift the trailer onto jack stands or use a PWC stand to remove weight from the tires and suspension.

How often should I run my jet ski during winter storage?

Generally, you should not start the engine out of the water, since running it dry can damage the impeller and cooling components. Unless you use a proper flush setup per your manual, leave the engine off until spring.

What parts should I replace during the off season?

Common winter upgrades include spark plugs, fuel filters, oil filters, impeller and wear rings, cables, and gaskets or seals. Inspect each item during winterizing, and replace anything worn so you are not stuck waiting on parts in spring.