Quicksilver Blog

How to Winterize Your Mercury Pro XS Outboard

At the end of the boating season, it can be all too easy to pull your boat out of the water and forget about it until the next season arrives. Don’t fall into that trap. Spending a few hours in the fall properly preparing for the offseason can save you a lot of time and money when it’s time to hit the water next spring.

This step-by-step video demonstrates the process of winterizing a Mercury® Pro XS® outboard using a variety of Quicksilver® maintenance products. It’s similar for many other Mercury and other brand four-stroke outboards. See your owner’s manual for a complete long-term storage service schedule for your engine model. Follow these basic steps to winterize any outboard:

Treat the Fuel System

After changing the fuel filter, add fuel stabilizer such as Quicksilver Quickstor® Fuel Stabilizer to fresh fuel (use non-ethanol fuel if available) in the tank. Run the motor for a few minutes to circulate stabilized fuel through the motor and fuel system.

Change the Oil and Filter

The motor’s oil and filter should be changed every 100 hours or once a season, regardless of how many hours it was actually used. Long-term storage with used oil can expose internal components to moisture and acidic combustion byproducts, which can cause corrosion. Quicksilver Oil Change Kits, available for many popular Yamaha® and Mercury outboards, make oils changes easy. Each kit includes Quicksilver 4-Stroke Marine Engine Oil, a premium oil filter and a new drain plug seal in a convenient package. After you change the oil, briefly start the motor to circulate the fresh oil and check for leaks.

Replace the Gearcase Lube

The gear lube in the outboard lower unit should also be changed every 100 hours or at least once a season. As you drain the old lube, inspect it carefully. Gear lube that appears milky or creamy may indicate the presence of water. That’s an indication the propeller shaft seal is damaged and allowing water to contaminate the lubricant, which could cause severe damage to the gears. Water in the gear lube can also freeze and expand during storage, potentially cracking the gearcase. If water intrusion is suspected, a pressure check of the gearcase should be completed by an authorized dealer. If the old lube is clear, refill the gearcase with fresh lubricant using a quality marine-specific product such as Quicksilver Premium Gear Lube, following the instructions in your owner’s manual.

Protect the Engine Internals

For long-term storage, internal engine components should be treated with engine oil or fogging oil to prevent corrosion. Remove the spark plugs and inject approximately one ounce of engine oil or spray fogging oil directly into each cylinder, following the directions on the can. Use a fogging oil product that is specially designed for use during winterization, such as Quicksilver Storage Seal. Whichever method you choose, rotate the engine flywheel manually a few revolutions to distribute the oil or spray evenly and replace the spark plugs.

Pro Tips

Here are some additional steps to include in your end-of-season outboard maintenance routine:

  • Grease the prop shaft and other points: If you removed the propeller to change the gear lube, it’s a good time to check the hub kit, inspect the seal for fishing line and grease the prop shaft with a quality marine grease like Quicksilver 2-4-C. While you have the grease gun out, hit the other main lubrication points, including the steering linkage and tilt/trim mechanism. (add link to video)

  • Check anodes: Inspect your sacrificial anodes for wear or damage. Anodes may become coated with a thin film of scum in some water conditions. This film can be removed with a stiff brush. Clean or replace as necessary.

  • Touch up paint: Exposed aluminum on the gearcase or skeg can lead to corrosion. Touch up the paint with Quicksilver primer and paint products

  • Use Corrosion Guard: For maximum corrosion prevention, spray Quicksilver Corrosion Guard Heavy Duty on the gearcase, tilt and trim motor, exposed electrical connections and other surfaces that operate in the water. Avoid covering anodes. Apply Quicksilver Corrosion Guard Engine Protect to under-cowl areas, avoiding belts and the air intake.

  • Store upright: Outboards should be stored in a vertical (upright) position to allow water to drain from the motor. Water trapped in cooling passages or rainwater collected in the propeller exhaust outlet can freeze and cause damage.

  • Battery storage: Fully charge your batteries, disconnect them from the boat and place on a maintenance charger.

Completing a thorough winterization process before putting your outboard away at the end of one season will help ensure that it’s ready to go for the next one.