This is how to clean your lawn mower for winter without damaging the engine, according to experts

The last mow of the year is done, and the job most gardeners save for October follows: scraping the packed grass from underneath the mower before it goes into the shed for winter.

With a petrol mower, the quickest way to get at it is usually to tip the machine on its side. But before you do, there's one detail worth checking.

The side you put down can matter more than you might think.

Get it wrong, and you may not notice anything immediately. The real surprise can come months later, when you pull the mower out for its first cut of spring and it suddenly starts smoking or refuses to start.

Fortunately, figuring out the right way to tip it doesn't take long.

Find the right side before you tip it

On many walk-behind petrol mowers, the air filter and carburettor should face upward when the machine is tilted. Consumer Reports gives the same general advice and recommends checking the owner's manual first.

Honda, for example, specifically tells owners to tilt certain mowers with the carburettor side up when clearing a clogged deck. Briggs & Stratton similarly advises keeping the spark plug facing upward if its engine has to be tilted.

The important word here is your mower. Designs differ, so check the owner's manual before tipping it rather than assuming the same position works for every model.

The reason for the caution is oil. Tilting an engine can allow oil to move into places it shouldn't, potentially leading to smoke or starting problems.

A few safety steps first

Let the mower cool before you start working around the engine and blade.

Then disconnect the spark plug wire on a petrol mower. Consumer Reports recommends this as an additional precaution before cleaning underneath.

Wear sturdy gloves and keep your hands away from the blade. For dried-on grass, use a plastic scraper or stiff brush rather than trying to pull the clumps off by hand.

It's also worth checking the oil level before putting the mower away. Briggs & Stratton notes that an overfilled crankcase can contribute to white or blue smoke.

Clean the deck without inviting rust

There's a good reason to remove all that dried grass before winter. Moist clippings left against the underside of a mower deck can contribute to rust and corrosion.

For stubborn buildup, Consumer Reports recommends a plastic scraper or bristle brush rather than a metal scraper, which can scratch the deck.

Don't automatically reach for the garden hose, though. Whether a mower can safely be rinsed underneath depends on the model, so check the manufacturer's instructions first.

If you do use water, leave the mower clean and dry before storing it.

Already tipped it the wrong way?

Don't panic if you've already laid the mower down on the wrong side.

Put it back on level ground and check the oil level and air filter. If oil has moved into the wrong place, the engine may produce white or blue smoke when restarted. Briggs & Stratton says smoke caused by tilting should normally clear after the mower runs for a few minutes on a flat surface.

If the smoke doesn't clear or the mower won't run properly, stop there and have a mower repair shop or dealer check it.

And if yours is a battery mower, this particular oil problem doesn't apply because there is no engine oil to move around. You still need to disconnect the battery before working underneath. EGO recommends removing the battery before cleaning.

So before you tip that mower over for its final clean of the season, take a few seconds to check the manual and identify the correct side.

That small step could save you from a smoky surprise when spring finally arrives.