Park the mower on a level surface and ensure that you use a suitable container to catch the dripping oil. Locate the oil fill cap and clean the area around it before taking out the dipstick to make sure that no foreign particles or contaminants enter the chamber. With the container positioned beneath the bottom of the drainage valve, remove the yellow cap and allow the oil to begin draining. You can then proceed to disengage the valve by pushing it inwards a bit and twisting it in the counter clockwise direction. Now pull out the drainage valve gently. Wait until all the oil has completely drained before removing the container.
Once all the oil has been completely drained, carefully lock the valve back in place by closing the drain chute and fastening it securely in place. Turn in the clockwise direction until the pin is secure. Now take out the drainage tubing and fit the yellow cap back into position.
Now proceed to fill fresh engine oil into the chamber through the dipstick tubing, taking care to ensure that no oil spills on the chassis of the unit. Do not overfill because oil will expand under operating conditions. Gauge the level of oil with the help of the dipstick and securely fasten the cap once you’re done. Turn on the engine and allow it to run for a minute or two.