A basic service on a petrol lawn mower usually means checking or changing the engine oil, spark plug and air filter, plus inspecting the blade. The exact oil, quantities, plug gap and service intervals must come from the engine manual.
Before working on the mower, remove the spark-plug lead. If the machine has electric start, isolate the battery as instructed as well.
1. Change the engine oil
Warm oil drains more easily, but the engine should not be dangerously hot. Follow the manual for the approved draining method and for whether the mower may be tilted in a particular direction.
Refill with the specified oil type and quantity, then verify the level correctly. Too much oil is not better.
2. Inspect or replace the spark plug
With the ignition lead disconnected, remove the plug using the correct socket. Inspect the electrodes and compare the plug type and gap with the engine specification.
3. Check the air filter
Paper and foam filters are not serviced in the same way, so do not automatically wash whatever you find. Clean or replace the element according to the engine manufacturer's instructions.
4. Inspect the blade
This is the part where I am least interested in improvisation. Disconnect the ignition first. If the mower needs to be tipped over, follow the manual so oil or fuel does not end up where it should not.
Check the blade for heavy wear, bends, cracks and damage. A dull but otherwise sound blade can be sharpened and balanced. A damaged blade should be replaced.
Why do it yourself?
Most of a routine mower service is inspection and a few simple consumables. Doing it myself gives me a better idea of the machine's condition and makes it much easier to notice small problems before they become expensive ones.
But the manual wins every argument here: engine designs differ, and generic internet instructions should never override the service procedure for your specific mower.
