A large part of lawn mower maintenance is changing the oil. A lawn mower's engine oil should be changed after the first 5 operating hours and then every 50 hours of operation or every season. In dusty or dirty conditions, oil changes may need to be more frequent.
If operating under heavy loads, extreme use, or high temperatures, engine oil should be changed every 25 operating hours.
As per owner's manual
- Run the engine for a few minutes to warm the oil. Warm oil flows better and will carry more contaminates.
- Stop engine and wait for moving parts to stop.
- Disconnect the spark plug wire.
- Remove drain plug and drain oil. Some mowers don't have plugs and need to be tipped over to drain oil out of the dipstick/filling port. Refer to owner's manual to avoid spilling gas or contaminating air filter.
- Install drain plug or return mower to operating position.
- Fill the crankcase to the "Full" line on the dipstick. Use oil recommended by the owner's manual and add a little at a time until full.
- Install dipstick
- Use a rag to wipe up any spilled oil.
- Recycle used oil according to local ordinances. Do not dump used oil down the drain!