If you don't give your lawn mower a little love in the form of regular maintenance, it will stop returning the favor.
The first step is to get all the tools and equipment you'll need. These include a power drill, work gloves, a blade sharpening kit, a torque wrench (or a socket wrench in a pinch) and a wooden block. Consider having a rubber mallet on hand, too. Other items include a plastic drip tray, motor oil and a container for waste oil.
First try blowing dirt and old grass clippings out with the leaf blower. If that doesn't work, scrape debris away with a putty knife. The last resort is to spray it with a garden hose. Unless your mower has a special washout hose connector, you risk damaging the engine, wiring and other sensitive parts.
One sure way to get rid of dirt is to wash your mower by hand with a damp rag.
Next you'll want to change your lawn mower's oil. Before you do that, lower its viscosity by running the engine for a few minutes.
Find the cap that covers the oil filler tube. It's usually black and doubles as a dipstick to check the oil level.
Carefully tip the mower on its side with the oil filler tube pointed at your drip pan. If the sludge that comes out looks as dark and dingy as this, you'll know an oil change was long overdue.
Don't pour old lawn mower oil down the drain. Dispose of it responsibly by collecting it in a container made for the job. You can then give full containers to a licensed disposal center.
Next add clean oil to the mower. Check with your mower's manual to confirm the right type and right amount of oil to add.