How To Check and Change the Oil Filter in a Lawn Mower

With warmer weather just around the corner and things starting to green up, homeowners everywhere have lawn mowers on their minds. Before taking your gas-powered, walk-behind or riding lawn mower out for the first time, be sure it’s stocked with fresh oil and a new filter.

All gas-powered riding lawn mowers have oil filters, but most walk-behinds don’t. So if you own one of the latter, you’re probably off the hook, although you’ll still need to change the oil regularly. Electric mowers don’t need engine oil or filters.

It’s fast and easy to change the oil filter in your lawn mower. It might not seem important, but it’s not something you should skip.

When I was 18, I helped an elderly neighbor split some firewood, then offered to cut his grass. He had an old Cub Cadet riding mower. Trouble was, the mower wouldn’t run properly. Turns out he changed the mower’s oil regularly, but not the filter, which was clogged for so long it damaged the engine. My neighbor ended up buying a new mower.

Avoid similar misfortune by learning how to check and change your lawn mower oil filter.

Where Is the Filter in a Lawn Mower?

It varies from one mower to the next. Look for a cylindrical metal object between two and three inches in diameter threaded into one side of the machine. This is the oil filter.

If you have a walk-behind mower and don’t see such an object, your mower doesn’t need a filter. If your machine does have an oil filter, here’s where to find it.

Walk-behind mowers

The cylindrical metal filter will be threaded into one side of the machine, most likely on the same side as the dipstick and oil cap. It’ll be hard to miss.

Riding mowers

It should be on the right side of the machine near the back, just above the oil drain hose or plug. Look just behind the right rear wheel. If you don’t see it there, check the left side.

When Should I Change the Lawn Mower Oil Filter?

Once every 50 hours of run time, or once per mowing season, whichever comes first.

How To Change a Lawn Mower Oil Filter

The steps are basically the same whether it’s a riding mower or a walk-behind. Always change the oil and filter at the same time, because if one is bad, the other will be too.

You’ll need an oil drain pan (any large plastic container will do), a jug or two of new oil (synthetic SAE 5W-30 is a safe bet for most mowers), a funnel, an oil filter wrench and a new filter. Check your owner’s manual to be sure you buy the right oil and right size filter for your mower.

• Locate the oil drain plug or hose on the side of the mower. Look near the back on riding mowers, and underneath the mower deck for push mowers. Some push mowers don’t have drain plugs; these need to be tipped on their side and drained from the oil fill port.
• Drain the old oil into your drain pan.
• Find the filter and unthread it with your wrench. Be sure to position your drain pan underneath the filter before removing it, because it’ll probably drip some oil.
• Dispose of the old oil at your local hazardous waste depot. Take the old filter at your local recycling station, or bring it to the nearest vehicle service center; many take used filters.
• Open a jug of new oil and dip your finger in it. (Use rubber gloves if you want.) Spread the oil from your finger over the rubber seal on the threaded end of the new filter so it doesn’t bunch up.
• Put on the new filter, tightening it with the filter wrench.
• Open the oil fill port, insert a funnel, then fill it up with fresh oil. Check your owner’s manual to find out how much oil to use.

Best Lawn Mower Oil Filters

There’s not usually a huge difference in quality from one brand of lawn mower oil filter to the next. Over the years I’ve used half a dozen brands, and they all work pretty much the same. Still, I like Briggs and Stratton filters the best.

Why? Some filters show signs of wear on the rubber seals when I pull them off to replace them. The Briggs and Stratton filters on my mower have perfect-looking seals even after a hard season of mowing.