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Lawn Mower Oil Change

Doing a mower oil change especially on a modern mower is a gift, the manufacturers are making them so diy user friendly, I doubt you'll need a tool.

So when should you do a mower oil change? Lawn mower engine oil should changed at least once per season or every 50 hours of operation. Most engines will take a !/2 quart (.6lt) of 10w30 engine oil.

If your yard is challenging terrain, hilly, over an acre, dusty, then a second oil change mid way through the season will help protect the motor. Clean the air filter regularly, about every 25 hours, more often in very dry dusty conditions.

Ideally a mower needs a full tune-up at the start of the season and it's only a little more work than an oil change.

When to Tune-up

This is a question I get a lot. I tell my customers service your mower at the start of the new season before the first cut. Mowers that overwinter can often have issues that arise from being idle such as stale gas in the carburettor, sticking valves, sticking wheels, cables etc.

 

If the storage area isn't heated, moisture can collect inside the engine. That's why I recommend a tune-up in the spring.

 

Proper winterising will eliminate lots of problems, check out lawn mower winterising (internal link). If your mower is a tractor mower check out this guide riding mower maintenance (internal link).

When Buying a Mower

Consider some of the features that will make your life easier when it comes to repairs and tune-ups. Features to look for are: large easy to read dipstick; large fuel filler opening; fuel shut off valve; quick release air filter cover; carburetor fuel bowl drain plug.

 

Knowing how to service and repair your own mower is a useful skill. Four stroke lawn mower engines are simple and most are designed thoughtfully, so that the home owner can DIY service.

 

 

Tune-up Includes

Change engine oil; change plug; clean/replace air filter; fuel filter (if fitted); drain carburettor bowl; inspect and sharpen blades or replace; inspect drive belt; lube all axles and controls.

 

 

The Tools You Need

While doing an oil change likely won't require any tools, a tune-up will require just basic ones. Doing a tune-up might sound like a lot of work, but really it isn't. Its also not technical, and no special tools needed. Like many tasks, its about the right knowledge and good preparation.

 

If you need to buy tools, buy good quality kit, its a great investment that will pay for itself in no time. 

Tool List

This is the tool wish list, all are not strictly necessary except the first one: Wd40; socket set with plug sockets; selection of wrenches; selection of screwdrivers & torx drivers; pliers; inspection light; flat file; wire brush; oil catch; gloves; goggles; dust mask.

mower repair tools

Tools

Only basic tools are needed.

Tune-up Parts You Need

All engines will have a model code and date stamped. Briggs and Stratton stamp their codes into the metal valve cover at the front of the engine. Kohler have a tag and Honda have sticker on the body.

 

After you find these numbers, buying the tune-up kit on line is easy. Most mower engines are very common and so you won't have a problem getting a tune-up kit to match.

 

Tune-up kit includes: oil; plug; air filter; fuel filter (if fitted); new blade (optional).

 

Check out part numbers with your engine maker.

 

Briggs and Stratton specification

Honda specification

Kohler specification

Kawasaki specification

 

Honda model number location Honda model number Kohler model number Briggs model number

Engine Code

The engine code is handy to have when ordering a tune-up kit.

mower tune-up kit

Tune-up Kit

Tune-up Guide

Your mower may not be the same as the demo model but that's not important, the process will be close to identical no matter what model you have.

 

There are many different makes of mower and many are fitted with the very reliable Briggs and Stratton single cylinder engine. Kohler and Honda are also quite popular engines.

 

​If you can, run your engine for a short time to warm the oil, this helps in the draining process. Be sure to wear gloves and goggles when working with gas and in a well ventilated area. 

 

Remember to disable your mower by removing the plug wire before starting work.

mower engine

Engine 

Briggs and Stratton, Kohler, Kawasaki, Honda.

All engines are easy to work on and get parts for.

Ignition


mower plug wire

1 Wire

Remove the plug wire and leave it off until your ready to start the engine later in process.

mower gas tap mower gas line

2 Off

Turn off the gas tap, if fitted.

Or pinch the gas line gently with a grips.

When turning your mower over, always turn the carburettor side up.

mower plug

3 Plug

Remove and replace plug. Check that replacement plug is the same.

Thread in new plug by hand before using the plug tool.

Mower plug

4 Snug

Snug the plug down and give it a little tighten.. Not too tight!

Don't fit the plug wire just yet.

Gas & Air


gas filter

5 Remove

Not all mowers will have a gas filter like this.

Gas filters may be directional, and if so will have an arrow which points to the carburettor.

Ride-on gas filters

6 Replace

Some filters will be built into the gas line, these type filters can be cleaned and reused.

mower gas tank

7 Clean

Some gas tanks will have a filter mesh screen at the bottom.

You may have to remove the tank to clean, depending how bad it is.

mower air filter

8 Replace

Remove & replace the air filter.

Clean the air box being careful not to allow dirt into the carburettor.

Blade Sharpening


mower blade

9 Inspect

Check your blade for damage or excessive wear. If worn, replace.

A new blade will be easier on the mower and your lawn.

mower blade

Bent

Never attempt to repair a bent blade, this will weaken the metal and can lead to injury.

Mower blade

Balance

Removing Deck blades for sharpening and balancing is advised.

If however, the blades are in good condition, you can sharpen in place.

mower blade

10 Flat

Sharpening your blade is done with a good quality flat metal file.

File the face of the blade to remove any small nicks. 

mower blade sharpen

11 Bevel

Now we will file at the same angle as the bevel, some blades will have the bevel facing the other way.

mower blade

12 Dress

Now dress the opposite side to remove the burrs.

A sharp blade is the secret to a beautiful healthy lawn, and it extends the life of your mower.

Belt Inspection


Mower belt

13 Check

Most mowers will have a belt to drive the mower.

Check the condition the belt and the pulleys.

mower belt

Flat Spot

These belts have a difficult job and can be the cause of various issues.

Regular inspection will tell you if your belt is at the end of its life.

Mower belt

Blistering

Things to look for are flat-spotting, glazing, cracking and fraying.

Mower belt

Glazing

Worn or damaged belts cause slip, which in turn will cause vibration.

The vibration can if ignored go on to cause lots of other issues.

Mower belt cracked

Cracking

Better to take care of this now, waiting for it to break can cause other damage.

Lubrication


mower oil drain lawn mower oil chart

14 Drain

Drain the oil while the engine is still warm, this helps the draining process.

add oil

15 Add

Add oil a little at a time, and check the level. Over filling is not good for the engine.

It will cause oil leaks, misfiring and lots of smoke.

Most small engine mowers will take a little over half a quart (.6lt) of 10w30 engine oil. Yes you can use car engine oil.

mower dip stick

16 Check

Do not thread in dipsticks to check the level, just push in and remove to check.

The full level on this dipstick is at the top of the hatched area.

Mower axle

17 Axle

Spray all controls with Wd40.

Spray front & rear Axles also. Wd40 lubes and protects from rust.

That's it, Nice work!

Related Question

How much oil does a push mower take? Most mowers will take about half a quart of oil or .6 of a litre from empty. Over filling will cause the engine to smoke.

Can I use 5w30 engine oil? Yes, 5w30 or 10w30 engine oil is good for a lawn mower engine.

Auto Technician and Writer at | Website

John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.