How to Winterize a Lawn Mower

What You’ll Need (tools/parts)

• Fuel stabilizer (ethanol-free recommended) or a fuel can for draining
• Engine oil (check your mower’s manual for correct weight, e.g., SAE 30 or 10W-30)
• Oil drain pan (shallow, wide, and clean)
• Funnel (for adding stabilizer or fresh oil)
• Spark plug wrench or socket set (typically 5/8 inch or 13/16 inch)
• New spark plug (optional, but good practice)
• Air filter (replace if dirty; foam or paper type, per mower)
• Blade removal tool (socket or wrench, plus a block of wood to lock blade)
• Wire brush or putty knife (for deck cleaning)
• Steel wool or a rag with light oil (for metal parts)
• Battery charger/tender (if mower has an electric start battery)
• Multimeter (optional, for battery check)
• Owner’s manual (for specific capacities and torque specs)

Safety First

• Disable ignition: Remove the spark plug wire and secure it away from the plug to prevent accidental starting. Even if you think the mower is off, the magneto can still produce a spark.
• Work in a ventilated area: Gasoline fumes are flammable and toxic. Never work near open flames, pilot lights, or while smoking.
• Let the engine cool: Hot oil and exhaust components can cause severe burns. Wait at least 30 minutes after last use.
• Use proper lifting techniques: Mowers are heavy; lift with your legs, not your back. Consider using a ramp or jack for deck removal.
• Secure the mower: If tilting the mower, tip it with the air filter and carburetor facing upward to prevent oil or fuel from flooding the intake. Use a block or stand.
• Handle fuel safely: Use approved containers. Drain fuel only into a metal or approved plastic container. Never store gasoline near water heaters or furnaces.
• Wear gloves and eye protection: Oil, fuel, and sharp blades are hazards. Safety glasses and mechanic’s gloves are recommended.
• Battery safety (electric start): Disconnect the negative terminal first. Batteries can produce explosive hydrogen gas; avoid sparks near the battery.

Step-by-Step Instructions

1. Run the mower dry (or treat the fuel)

   • Option A (preferred for carburetor health): Run the mower until the fuel tank is empty and the engine stalls from fuel starvation. This prevents stale fuel from gumming up the carburetor.
   • Option B (if you can’t run dry): Add fuel stabilizer according to the manufacturer’s ratio (typically 1 ounce per 2.5 gallons). Fill the tank to minimize air space, then run the mower for 5 minutes to circulate the stabilizer through the carburetor.

2. Drain or change the engine oil

   • Warm the engine briefly (2–3 minutes) to thin the oil, then shut it off. Place the drain pan under the oil drain plug (or dipstick tube if your mower has one). Remove the plug and let oil drain completely. Replace the plug. If changing oil, refill with fresh oil to the correct level (check dipstick). Dispose of old oil at a recycling center.

3. Remove and replace the spark plug

   • Use a spark plug socket to remove the plug. Inspect the electrode: if it’s black, oily, or worn, replace it. Gap the new plug to spec (usually 0.030 inch, but check manual). Install by hand to avoid cross-threading, then tighten 1/8 to 1/4 turn with a wrench. Reattach the spark plug wire after installation.

4. Clean or replace the air filter

   • Remove the air filter cover. If it’s a foam filter, wash with warm soapy water, rinse, dry completely, then lightly oil with air filter oil. If it’s a paper filter, tap it gently to remove debris—replace if it’s dirty or damaged. Never run the mower without a filter.

5. Clean the mower deck

   • Tip the mower on its side (air filter up). Use a wire brush or putty knife to scrape off grass clumps, mud, and debris from the underside of the deck. Rinse with a hose if needed, but dry thoroughly to prevent rust. Apply a light coat of silicone spray or paint to bare metal.

6. Remove, sharpen, and store the blade

   • Block the blade with a piece of wood to prevent rotation. Use a wrench to loosen the center bolt (usually left-hand thread—turn clockwise to loosen). Remove the blade. Sharpen it with a file or grinder, balancing it afterward. Apply a thin coat of oil to prevent rust. Store the blade in a dry place, or reinstall it if you prefer (tighten to 30–40 ft-lbs).

7. Lubricate moving parts

   • Apply a few drops of light oil to all pivot points: throttle cable, brake linkage, wheel axles, and height-adjustment levers. Wipe off excess to avoid attracting dirt.

8. Inspect and replace belts/cables (if applicable)

   • Check the drive belt for cracks, fraying, or glazing. If worn, replace it. Check the control cables for kinks or rust; lubricate or replace as needed.

9. Charge and store the battery (electric start)

   • Remove the battery. Clean terminals with a baking soda/water paste if corroded. Charge it fully (12.6V or higher). Store it in a cool, dry place (above freezing) and connect a trickle charger or maintainer monthly.

10. Store the mower properly

    • Wipe down the entire mower with a rag. Store it in a dry shed or garage, off the ground if possible. Cover with a breathable tarp (not plastic, which traps moisture). If storing with fuel, add stabilizer and fill the tank to prevent condensation.

Tips & Common Mistakes

• Mistake: Skipping fuel treatment. Stale gas is the #1 cause of spring no-start issues. Always stabilize or drain fuel.
• Mistake: Tilting the mower wrong. Tilting with the carburetor down can dump oil into the air filter and exhaust, causing smoke or hydro-lock. Always tip with the air filter up.
• Mistake: Over-tightening the spark plug. Too much torque can crack the ceramic insulator. Hand-tighten plus a slight turn is enough.
• Tip: Label your fuel can. If you store mixed fuel for a two-stroke mower, label it with the date and mixture ratio.
• Tip: Use a fuel stabilizer with ethanol protection. Ethanol attracts moisture and can damage carburetors. Products like Sta-Bil or Sea Foam help.
• Common mistake: Leaving the blade on. A sharp blade left on can rust or be a safety hazard. Removing it also makes deck