Tecumseh manufactures a variety of small engines for use in lawnmowers, as well as other lawn and garden equipment. Most of these Tecumseh engines are four-cycle engines, which have a reservoir for motor oil that keeps the engine's components lubricated. Occasionally, the motor oil in these Tecumseh engines needs to be drained and replaced. You can change Tecumseh lawnmower oil and replace it with fresh oil in a few minutes with some common hand tools.
Disconnect the spark plug wire from the spark plug, by pulling on the black rubber boot that covers the tip of the spark plug.
Place the four wheels of the mower on breeze blocks or large blocks of wood.
Tilt the mower onto two wheels so you can access the underside of the mower deck. Near the centre, locate the drain bolt. It will be about 1/2-inch in diameter, and have either have a four-sided head that protrudes downward, or a six-sided large recess to accept a large Allen wrench.
Select the appropriate Allen wrench or open-end wrench for your Tecumseh engine's plug. Turn the plug counterclockwise to loosen it slightly. Do not remove it completely at this point, as you only want it loosened to the point of being able to turn it by hand.
Place the mower back on all four wheels on the blocks. Position an oil pan with a reservoir between the blocks directly underneath the oil plug. Then, loosen and remove the oil plug by hand, allowing the oil to drain directly into the oil pan. Let the oil drain for about five minutes, until all of the available oil has drained from the engine's reservoir.
Replace the oil plug. Tighten it with the Allen wrench or open-end wrench. Lift the mower from the blocks and onto the ground.
Remove the oil fill plug and dipstick from the top of the mower. Pour in about 1/4 of the quart of oil. Replace the dipstick, and check the oil level. Continue filling the oil reservoir and checking the dipstick in small intervals until the dipstick registers that the oil in the crankcase is full. Do not overfill the reservoir, as this could damage the engine.
Reconnect the spark plug wire to the spark plug. Test the engine.
Pour the used motor oil from the drain pan into a sealed plastic container. Take it to the nearest oil collection facility.
Never dump used motor oil on the ground. Capture the oil in a sealed container and take it to a local recycling facility.