Things You'll Need
Plastic oil pan
When changing the oil in the John Deere JS20 lawn mower, you have to know that there's not a drain plug on the engine that allows the oil to easily pour out. The oil comes out of the place where you put it in. You have to be able to lift carefully and aim a little, depending on the size of your oil pan, so you don't make an oily mess in your work area.
Run the lawn mower for about five minutes to heat the engine so the oil is thin and more fluid-like and then turn it off. Thick oil is harder to remove from an engine than thin oil.
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Remove the spark plug wire from the spark plug. This ensures that the engine can't possibly start accidentally.
Place a plastic oil pan on the left side of the lawn mower, where the oil filler cap is located.
Remove the oil filler cap/dipstick and wipe it off with an old cloth or shop towel.
Tilt the engine and allow the oil to run out of the oil filler tube completely.
Set the lawn mower down when the oil is all the way out.
Wipe off any excess oil.
Pour oil into the oil filler tube, occasionally checking the level with the dipstick. When the oil reaches the "Full" line, replace the oil filler cap/dipstick.
Connect the spark plug wire to the spark plug.
Start the lawn mower and run it for a few minutes so the new oil can circulate through the engine and lubricate all the internal parts.
Take the old oil and its container to a recycling center that disposes of used oil. You can also dispose of the oil at car parts stores, including AutoZone and Advance Auto, which both recycle used oil for free.