Engines need a continuous supply of fresh oil to function correctly. The mower owner needs to periodically add and/or change the oil to keep the mower running well. Oil lubricates engine parts which reduce friction. Like a car, the riding lawn mower will use a specific grade of motor oil. The oil capacity of various mower models differs. Determine the proper oil and capacity for the mower by referencing the owner's manual. If the manual has been lost, consult the website of the manufacturer for this information. Using the wrong oil can ruin your engine. Also, check the manual for information on the oil filter, if the mower has one. It needs replacing when the oil gets changed.
Unlike a car, riding lawn mower doesn't require frequent oil changes. Generally, they receive new oil once per year or every 50 to 100 hours of use, depending on the model.
What to Do if the Manual Does Not Specify an Oil
In some cases, the manual does not specify an oil. In these cases, determine the appropriate oil based upon a combination of the climate in which the mower is used and its engine type – single or twin cylinder.
- SAE 30: Works well in warmer temperatures and it's the most common small engine oil.
- SAE 10W-30: Good for cold weather starting but works for various temperature ranges. Can increase oil consumption.
- Synthetic SAE 5W-30: This works well at all temperatures and provides improved starting. It lowers oil consumption.
- SAE 5W-30: Works well at very cold temperatures.
- Vanguard 15W-50: This works at various temperatures and performs the best for continuous use, i.e. commercial lawn cutting.
Gather your supplies before beginning. You'll need the following items:
- engine oil,
- drain pan,
- drain tube or Arnold Siphon Pump,
- oil filter,
- strap wrench,
- work gloves.
How to Check the Oil Level
Determine if the mower has enough oil in it by checking it with a dipstick. Do this before each use. If the user has a just purchased riding lawn mower, these do not normally come with oil in them. Check though.
- Draw the dipstick out of its storage pocket near the engine.
- Wipe it clean with a cloth.
- Re-insert it to obtain an accurate oil measurement.
- Draw it out again and check the oil residue against the line indicators on the stick. One line will represent a properly full oil chamber while another will represent a too-low chamber. Each line is marked.
- Wipe off the dipstick again.
- Re-insert it in the storage pocket.
How to Change the Engine Oil
Those who have changed their car oil before will find this a similar process. Seeing it written out in steps makes it look like it will take a long time, but the process really only takes a few minutes.
- Park the riding lawn mower on a level, flat ground.
- Turn off the motor.
- Remove the key.
- Engage the parking brake.
- Open the hood after the engine has cooled.
- Disconnect the spark plug wire.
- Clean the area that includes the oil fill tube, oil drain and oil filter. This removes debris that could otherwise fall into the drain while changing the oil.
- Remove the dipstick from the oil fill tube. Use a cloth to wipe it off. Set it aside.
- Place a 64-ounce capacity container underneath the oil-drain sleeve. It can also rest beneath the Arnold Siphon Pump.
- Remove the drain plug. The oil will flow out into the container. This takes a few minutes.
- Wipe down the oil drain area and replace the drain plug.
- Remove the Arnold Siphon Pump or drain sleeve.
- Remove and properly dispose of the old oil filter.
- Wipe the area clean around the housing for the oil filter with a clean cloth.
- Spread a light coating of the new oil filter's gasket with the new engine oil. This provides a proper seal for the filter.
- Slip the oil filter into place until it touches the oil filter adapter.
- Use an oil filter wrench to tighten it.
- Pour new oil into the oil fill tube. Use only the prescribed amount.
- Check for leaks underneath, around the oil filter and drain plug. Wait a couple of minutes before conducting the check.
- Using the dipstick removed earlier, check the riding lawn mower engine oil level. If it does not yet reach the “full” line, add a little more and re-check it.
- Wipe clean the dipstick, replace and tighten it.
- Re-connect the spark wire to the spark plug.
For those who learn better visually, Sears posted a video tutorial of the process.
It can be viewed here.