Step-by-Step Guide to Changing Your Lawn Mower Oil

Learning how to change lawn mower oil step by step is one of the most important maintenance tasks you can perform. Fresh oil lubricates the engine’s moving parts, reduces wear, and helps it run cooler and more efficiently. While the process is straightforward, doing it correctly ensures your mower stays reliable for seasons to come. This guide will walk you through the complete process, from preparation to the final check.

Preparation and Safety First

Before you start, gather your supplies. You’ll need the correct type and amount of oil for your engine, a new oil filter (if your mower has one), a drain pan, a funnel, rags, a wrench or socket to fit the drain plug, and gloves. Always work in a well-ventilated, flat area. For a complete list of useful items, see our guide on lawn mower maintenance tools.

How to Change Lawn Mower Oil Step by Step

Follow these steps in order for a clean and complete oil change. This task is a cornerstone of routine mower maintenance.

1. Warm Up the Engine

Run the mower for 5-10 minutes. Warm oil flows more freely and will carry more suspended contaminants with it when drained, resulting in a more effective change. After warming, turn off the engine, disconnect the spark plug wire, and move the mower to your level work area.

2. Locate the Drain Plug and Prepare to Drain

Consult your owner’s manual to find the oil drain plug. It’s typically on the underside or lower side of the engine crankcase. Place your drain pan directly underneath it. Some walk-behind mowers may not have a drain plug; instead, you may need to carefully tip the mower on its side (with the air filter and carburetor facing up) to drain the oil out of the fill tube. Know your mower’s design before proceeding.

3. Drain the Old Oil

Using the correct wrench, carefully loosen and remove the drain plug. Allow all the old oil to flow completely into the pan. This may take a few minutes. Once drained, clean the drain plug area and the plug itself with a rag, checking its washer for wear. Reinstall and tighten the plug securely by hand, then give it a final snug turn with the wrench—avoid overtightening. If your mower has a spin-on oil filter, this is the time to remove it with an oil filter wrench, ensuring the rubber gasket comes off with the old filter.

4. Replace the Oil Filter (If Applicable)

Before installing the new filter, dab a small amount of clean oil on your finger and wipe it onto the new filter’s rubber gasket. This helps create a good seal. Screw the new filter on by hand until the gasket makes contact, then tighten it an additional three-quarter turn as per typical manufacturer guidance. Do not use the wrench for the final tightening unless the manual specifically instructs you to do so.

5. Refill with New Oil

Locate the oil fill cap, usually on top of the engine. Insert your funnel and slowly pour in the manufacturer-recommended type and amount of oil. Using the wrong oil can harm your engine. Refer to your manual for the exact specification (e.g., SAE 30, 10W-30) and capacity. It’s better to start by adding slightly less than the full amount.

6. Check the Oil Level

Replace the fill cap securely. Wipe the dipstick clean, reinsert it fully, and then pull it out again to check the level. The oil should be between the “Full” and “Add” marks on the dipstick. Add small amounts of oil as needed to reach the correct level, checking after each addition. Never overfill. Reconnect the spark plug wire once you are finished.

Proper disposal of the old oil is crucial. Never pour it on the ground or into a drain. Take the used oil in a sealed container to a local auto parts store, service station, or recycling center that accepts it. Many offer this service for free.

When to Perform This Task

Knowing when to change the oil is as important as knowing how. Frequency depends on your mower’s engine type and how often you use it. For specific guidance, our article on how often you should change lawn mower oil covers the common intervals and factors to consider. An oil change is also an excellent time to tackle other maintenance, like checking the air filter or inspecting the mower blade for damage.

Frequently Asked Questions

Can I use car oil in my lawn mower?

You should only use the oil type specified in your lawn mower’s owner’s manual. While some small engines can use common automotive oils like SAE 10W-30, many require a specific small-engine oil formulation. Using the wrong oil can affect performance and void warranties.

What if my mower doesn’t have a drain plug?

Many older or simpler walk-behind mowers require tilting to drain the oil. Always ensure the carburetor and air filter side is pointing up to prevent fuel and oil from flooding these components. Tilt the mower carefully over your drain pan until the oil flows from the fill tube. Refer to your manual for the approved method.

How do I know how much oil to put in?

The exact capacity is listed in your operator’s manual, often in ounces or quarts. If you no longer have the manual, you can often find this information by searching the engine model number online. The safest method is to add oil slowly and check the dipstick frequently to avoid overfilling.

Do I need to change the oil filter every time?

It is highly recommended. The oil filter traps contaminants, and changing it with every oil change ensures your new oil stays clean. If your mower has a filter, it’s a small additional cost that provides significant protection for your engine.

What should I do with the old oil and filter?

Used motor oil is a hazardous waste. Pour the cooled oil from your drain pan into a sealed, leak-proof container (like the empty new oil bottle). Many auto parts stores and service centers accept used oil and filters for recycling at no charge. Never dispose of them with regular household trash.

Mastering this simple process is key to keeping your mower running well. For a broader look at keeping your equipment in top shape, explore our complete guide on how to maintain a lawn mower, which includes other vital tasks like sharpening the blades and cleaning the mower deck.