Why Winterization Matters
I have spent over twenty years in the shop, and I can tell you that my busiest time of year isn't actually the summer mowing season—it is the first two weeks of spring. Every single year, the phone starts ringing off the hook the moment the grass hits three inches high. Almost every call is the same: 'Derick, my mower won't start.' Nine times out of ten, that headache could have been avoided with an hour of work back in November. When you let a mower sit for months with old fuel in the tank and debris under the deck, you aren't just storing it; you are inviting corrosion, gummed-up carburetors, and rusted parts to take over. This guide will teach you exactly how to tuck your mower away so it stays healthy until you need it again.
The Fuel Problem: Your Number One Enemy
Modern gasoline contains ethanol, and ethanol loves moisture. Over the winter, that fuel draws water out of the air, causing it to phase-separate. This leads to sludge and varnish buildup in your carburetor jets. If you leave fuel in the system, you are essentially guaranteeing a rebuild come springtime.
How to Treat Your Fuel System
You have two options here. The best way is to drain the tank completely. Use a siphon pump to get the fuel out, then run the engine until it dies to clear the lines. Alternatively, if you prefer to keep the tank full to prevent condensation, use a high-quality fuel stabilizer. Add it to a fresh tank of gas, run the engine for ten minutes to ensure the treated fuel reaches the carburetor, and then shut it down. Pro Tip: Always fill your fuel tank to the brim if you choose the stabilizer method, as a full tank leaves less room for humid, moisture-filled air to settle inside.
Oil and Filter Changes
Think of the old oil in your crankcase like a dirty sponge. It contains combustion byproducts, acids, and metal shavings from the previous season. If you let that sit in your engine all winter, those acidic contaminants can eat away at internal components like your bearings and cylinder walls. Changing the oil and filter before storage ensures your engine rests in clean, protective fluid rather than a soup of chemical wear.
Cleaning the Deck and Chassis
We often ignore the underside of the mower, but wet grass clippings are highly acidic. When they sit on your steel deck all winter, they will eat through the finish and eventually the metal itself. Use a scraper to remove all built-up debris. If you use water, make sure to let the mower run for a few minutes afterward to heat up the deck and evaporate the moisture. Never leave your machine wet in a dark corner of the garage.
Battery Maintenance
Batteries have a natural discharge rate. If you leave yours connected, it will slowly drain until it falls below the threshold of being able to turn over the starter. Once a lead-acid battery goes completely dead, it often develops sulfation, which effectively kills the battery. Disconnect the negative terminal to prevent drain, or better yet, put it on a trickle charger or a smart battery tender. A battery tender will keep your battery at the perfect voltage level without the risk of overcharging.
Lubrication and Protection
Grease the zerks. Your spindles, pivot points, and front axle components need fresh grease. This pushes out any water that might have entered during washing or rainy mowing days. Once greased, wipe down the exterior with a light coating of wax or a silicone-based spray to protect the paint. Safety First: Always remove the spark plug wire before performing any maintenance under the deck to ensure the engine cannot accidentally start while you are working near the blades.
Common Mistakes to Avoid
One mistake I see far too often is storing a mower in a damp shed or directly on a dirt floor. Dirt acts as a sponge, pulling moisture up into your frame and electrical components. If you must store it on dirt, lay down a heavy-duty plastic tarp first. Another mistake is covering the mower with a plastic tarp without leaving airflow. This creates a greenhouse effect, trapping moisture against your machine and accelerating rust.
When to Call a Pro
If you find your engine oil looks like a chocolate milkshake, that indicates a head gasket leak or an internal seal failure—do not store it like that. If you notice fuel leaking from the carburetor during your prep, or if you aren't comfortable working with engine internals, call your local shop. Preventive maintenance in the winter is usually cheaper than a full overhaul in the spring. If you follow these steps, you will be the one person in your neighborhood who actually gets to start mowing on that first warm Saturday while everyone else is still waiting for their shop appointment.