If you’ve ever tried to start a zero-turn in April only to have it sputter, flood, or refuse to turn over at all, there’s a good chance the problem started the previous fall — not that morning. Winterizing a mower isn’t optional maintenance in Michigan. Between the freeze-thaw cycles, the humidity swings in a closed garage or shed, and months of sitting completely still, an unprepared mower takes real damage over winter. The good news is that doing it right takes about half an hour and a handful of basic supplies.

When to start

A good rule of thumb is to winterize as soon as mowing season is functionally over for you, not necessarily right after the first frost. In Dimondale and Ray Township, that’s usually sometime in October. Up in Houghton Lake, the season wraps earlier and temperatures drop faster, so it’s worth getting ahead of it by a couple of weeks. Waiting until the mower is already caked in frost makes the job harder and increases the odds you’ll miss something.

The step-by-step

Deal with the fuel first. This is the single most-skipped step, and it’s the one that causes the most spring headaches. Gasoline starts breaking down in as little as 30 days, and the ethanol blends most stations sell absorb moisture over time, which leads to varnish buildup in the carburetor and fuel lines. You have two real options: run the tank down and start the engine dry, or fill the tank completely and add a fuel stabilizer, then run the engine for a few minutes so treated fuel reaches the carburetor. Either approach beats leaving old gas to sit all winter.

Change the oil and filter. Old oil holds combustion byproducts and moisture that can corrode internal engine parts over months of inactivity. Fresh oil going into storage means a clean start in spring.

Check or replace the air filter. A season of clippings and dust will have taken a toll. A clogged filter come spring means a rough-running engine right when you need it most.

Pull the blades. Remove them, sharpen or replace as needed, and give them a light coat of oil before storage to prevent rust. This is also the easiest time to check the mounting hardware for wear.

Handle the battery separately from the mower. Cold temperatures accelerate battery discharge, and a fully dead battery over winter often means a full replacement in spring. Disconnect it, store it somewhere that stays above freezing, and put it on a trickle charger or battery tender if you have one. The same logic applies to anything else you’re putting away for the season — our guide to UTV battery life through a Michigan winter goes deeper on why stored batteries fail and how to prevent it.

Clean the deck. Caked-on clippings hold moisture against the metal all winter, which is exactly the environment rust needs. A thorough scrape and rinse (dried completely before storage) goes a long way.

Check tire pressure. Tires lose pressure naturally over months of sitting, and starting spring with underinflated tires affects handling and deck-height accuracy.

The mistakes that cost people the most

The two biggest ones: leaving untreated fuel in the tank all winter, and leaving the battery connected (even when the mower is off, small parasitic draws can fully drain a battery over several months). Both are avoidable in under five minutes each.

DIY vs. having it done

None of this is complicated, but it does take time, and skipping any one step is what usually causes the “why won’t this start” call in April. If you’d rather hand it off, OECo’s service department handles full winterization and spring startup service across all the equipment we carry. If you’re weighing that trade-off more generally, our breakdown of when mower repair is worth paying for covers where the line usually falls.

Frequently Asked Questions