It is easier to forget, but it is just as important to check the oil in your Toro lawnmower as it is to check the oil in your car. Low oil levels on your lawnmower increase its emissions, wear down the engine and if the levels are low enough the engine will seize and have to be replaced. In general, you should check your Toro lawnmower's oil after every five hours of use. The oil should be changed after every 25 hours of use.
Make sure that the engine is cool. If you have just used the lawnmower's engine, wait 20 minutes.
Locate the oil cap. It will be on the engine, but its exact location will vary from model to model. If you are unsure of where it is, consult your owner's manual.
Unscrew the cap and extract the dipstick.
Wipe the dipstick with a clean rag, stick it back into the oil reservoir and pull it out again.
Check the oil level. If the mower has sufficient oil, the dipstick will have oil on it on or around the "full" line. If the oil is low, but clean (clear), simply add oil bit by bit until the dipstick shows that the oil is at an appropriate level.
Check the oil consistency and color. Viscous dirty oil will have to be changed.