Storing mower in shed for winter

When it comes to winterizing, there are specific steps to properly store your lawnmower for the season.  You may find that following the steps in a strategic pattern helps you avoid missing one of the items.  It doesn’t matter whether you work top to bottom of the lawnmower, front to back, or side to side. Whatever works best for you is the way to complete all the work.

Item #1: Change the Engine Oil and Filter

Usually after a long summer of mowing, your engine oil is ready for a change before you store your lawnmower.  Most likely its color changed from golden brown to dark brown (or black).  That’s what happens over heavy use during hot summer months.  Oil breaks down with heat.  And used oil contains acids that corrode metal surfaces and internal engine components.  Before storing your mower, drain the old oil out and replace it with fresh AMSOIL Synthetic Small Engine Oil.  AMSOIL offers three engine oil viscosities, and your owner’s manual specifies which is best for your lawnmower.  Once you replace the engine oil, also add a new AMSOIL EA oil filter if your lawnmower requires a filter.

Item #2: Inspect the Air Filter

Oxygen is one of the components required for your lawnmower’s engine to run.  Having a clean air filter keeps the air supply flowing into the engine.  It also keeps the combustion happening inside the engine.  Over the summer months, your air filter becomes dirty with dust and gunk.  Clean the air filter for a couple years, but eventually the dirt builds up becomes too much.  At that point, it’s time to replace it with an AMSOIL air filter to prepare it for another mowing season.

Item #3: Clean & Protect the Mower Deck

The mower deck is an area of your lawnmower that may get neglected.  The top side is easy to see and can be cleaned easily.  But the underside is often full of grass clippings, leaves, and dirt.  This buildup tends to clog the mower, causing corrosion and rust when you store your lawnmower.  Cleaning the area is easy to do with a putty knife, scraper, or compressed air.  Once the buildup is cleaned out, rinse it clean with water from a hose.  Allow it to dry, then coat the surface with AMSOIL Mudslinger.  This will keep the surface coated for next year and reduce the buildup of clippings, dirt, and leaves.

Item #4: Inspect & Sharpen the Cutting Blade(s)

The cutting blade(s) on your lawnmower may be new and in great shape.  Every year you should inspect them for wear and determine how sharp they are.  Doing it when they are clean after preparing the mower deck is the perfect time.  Inspect them to ensure they will be ready to go next year.  If your blades appear dull, either sharpen them on the lawnmower, or remove the blade(s) to sharpen them.  An angle grinder or bench grinder will quickly sharpen the cutting edges.  If they are bent or chipped on the cutting edge, they may be too damaged to put back into service.  At that point, replace them with a new set.  The blades are most likely untreated, and the fresh cutting edge will be bare metal after you sharpen it.  You can use AMSOIL Heavy-Duty Metal Protectant to keep the edge from rusting while you store your lawnmower.

Item #5: Stabilize the Gasoline for Storage

Stabilize the fuel in your fuel tank to prevent it from degrading while you store your lawnmower.  As fuel degrades, it causes a gummy buildup that clogs your engine’s fuel supply lines.  If your tank isn’t full, fill your gas tank just below the full level with fuel.  Add AMSOIL gasoline stabilizer to the tank.  Follow the directions on the bottle for the amount to add based on your fuel tank size.  Lastly, run your engine for approximately 15 minutes to allow the stabilizer to mix with the fuel and cycle through the engine and fuel system.

Item #6: Clean or Replace the Spark Plug(s)

Spark plugs should last for years of service.  So, a newer lawnmower should just need the spark plugs cleaned.  You can use a socket and ratchet to remove the spark plug from each cylinder.  Be sure to inspect the plugs.  If the electrode has contamination or excessive wear, replace it.  If it is in good condition, brush it off and check the gap on the electrode.  The owner’s manual or label on the mower indicates the proper spark plug gap.  Worst case, you can probably find the specification online.  Your mower may have only one spark plug, or it may have multiple.  The process for removal, inspection, cleaning, or replacement is the same.

Do not reinstall the spark plugs yet. Proceed to the next item first.

Item #7: Fog the Engine Cylinders

Fogging the engine should be done after removing spark plugs from the lawnmower engine.  With the spark plugs removed, spray AMSOIL Fogging Oil into each engine cylinder.  The Fogging Oil protects the cylinder walls from rust and corrosion while you store your lawnmower.  It also helps prevent subsequent dry-start-induced damage in the Spring.  After spraying the Fogging Oil into each cylinder, use the pull cord to cycle the engine if your lawnmower does not have a battery.  If your lawnmower has a battery, try to start the engine which will cycle the engine.  It will not start without spark plugs.

Once the AMSOIL Fogging Oil is protecting each cylinder, reinstall the spark plug(s) and connect the spark plug wires.

Item #8: Remove the Battery

Hot and cold weather can shorten the life of your battery.  Leaving it sit all winter in the lawnmower may cause it to slowly drain the charge.  It could be completely dead come Spring.  Take the battery out of the lawnmower and place it in a somewhat climate-controlled environment.  Store it on a workbench in the garage or on a shelf where it isn’t going to see extreme temperatures. Don’t leave it next to open flames, the water heater, etc.  Before you store your lawnmower battery for the winter, give it a thorough cleaning.  Wipe the case down with a wet towel.  Clean the battery terminals to remove any deposits.  If there is corrosion on the battery terminals, scrub them with an old toothbrush and a baking soda/water mixture to remove it.  Or use a battery terminal brush to give them a scrub.

The terminals may or may not develop surface rust while in storage.  To prevent surface contamination, simple spray the terminals with a rust preventative spray such as AMSOIL Heavy-Duty Metal Protectant.  Lastly, if you have a battery tender to connect to the lawnmower battery, connect it to keep the charge full.

When the battery is out of the lawnmower, also clean the terminals on the battery cables and spray them with a protectant spray.  The area the battery sits in the lawnmower is usually full of grass clippings, leaves, and other debris.  You can clean most of the area by hand or with a vacuum.  That will prevent corrosion on any metal parts or tools in the area, and keep your battery area ready for Spring.

Item #9: Store Your Lawnmower in a Dry, Covered Area

Complete the maintenance above so your lawnmower is ready for winter slumber.  The best place to store your lawnmower is in a dry, covered area.  That can be in a covered garage, a carport, or under a tarp if that is the best you have available.  Keep moisture off of it to reduce corrosion from starting anywhere on the lawnmower.

Follow the above 9 tips to have your lawnmower winterized and ready for the cold winter storage.  Your local AMSOIL dealer can help you keep all of your lawncare equipment running smoothly with maximum protection.  You can feel confident that adding AMSOIL products at the end of your mowing season will keep your equipment ready for the next year of lawncare.  Contact your local AMSOIL dealer at Buy Great Oil for every product you need to keep your power equipment in tiptop shape.

Our Products

Motor Oils


Transmission Fluids

Filtration Products

Fuel Additives

Gear Lubes

Other Products

Compressor Oils