What Happens When There’s Too Much Oil in a Lawn Mower? + How to Drain Excess

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Properly maintaining a lawn mower is essential to ensure you get that clean and consistent cut for your lawn. But I’ve had moments during my mowing routine where I might have accidentally added more oil than needed into the tank.

So, what’s the plan if you find yourself with too much oil in your lawn mower? Here’s what seasoned landscapers and experienced gardeners like myself recommend.

Signs that Your Lawn Mower Has Too Much Engine Oil

First, you should check the mower’s engine components to ensure they are functioning correctly. Here is a list of common telltale signs when you’ve added too much oil to the lubricant tank.

overfilled lawn mower

#1: Engine Seal Damaged

Excess oil will cause malfunction and damage to the lawn mower engine seal. This usually happens when the lubricant passing through the oil filter is too hot, so being careful not to overfill. 

#2: Overheating Engine

An overheating engine is one of the most common problems in riding mower caused by adding too much oil than the recommended oil requirements for your mower. 

When the oil is too hot, it can cause the lawnmower engine to surge or seize up and not work correctly. In addition, too much oil can damage the seals, gaskets, and combustion chamber. At worst, the engine may even catch on fire. 

#3: Locked Up Engine

Your lawn mower may become hydro-locked if you’ve spilled too much engine oil. 

locked up lawn mower engine

This is where there’s oil overfill, causing the engine to no longer run. If this happens, I recommend taking your lawn mower to a repair shop to have the excess oil removed from your mower.

#4: Smoking Engine

Another common problem caused by too much oil is a smoking engine. This usually happens when the oil is overheating, causing a lawn mower to blow white smoke from its combustion chamber.  

#5: Malfunctioning Engine

Adding extra oil may result in problems with the spark plugs, fuel injection system, or other engine parts, causing the engine to malfunction.

In my experience, another sign of a damaged or bad engine is when the crankshaft repeatedly strikes bursting oil during operation. 

lawn mower engine malfunction

If you notice any of these problems, I suggest you take your lawn mower to a repair shop to have it checked out for engine block. Stop using your current engine oil and evaluate for compatibility. 

#6: Damaged Part/s

Check if your lawn mower shows signs of oil leak and inspect for damaged gasket or spark plug wire. This can be caused by overfilled oil tanks.

What Should I Do If I Added Too Much Oil to my Lawn Mower Engine?

It’s essential to know the signs of too much oil in a lawn mower particularly when readying your mower for the summer, so you can do proper oil removal and refill.

A distinct burning smell or even fumes coming from your engine is a telltale sign that you’ve spilled too much oil. It is especially true if you don’t regularly change your oil and the residue has built up.

If there’s too much visibly, you can start by removing the oil dipstick or cap first, then drain. Place enough oil and don’t exceed the maximum mark. Also, I clear the oil drops around the engine and air filter as a preventive measure. 

red lawn mower tune up

If you notice leaks from the engine, this can also be a sign that there’s too much oil in your lawn mower. If this is the case, you need to clean the leaking oil running down its side.

A low-level hum from the engine or even white smoke coming from it can indicate too much lubricant. I recommend you observe this as part of preventive measures against fire hazards. 

It’s important to identify and address these signs to prevent overheating your machine and avoid extra cost in repairs and maintenance. It would also be beneficial to check for equipment reviews from others who purchased the same brand. 

How to Remove Excess Oil From a Lawn Mower

Step #1: Wipe the Crankcase Area

If there is excess oil in your Troy Bilt riding lawn mower, I first suggest wiping the surplus lubricant. Use a turkey baster, clean rag, and paper towel to remove as much oil as possible from around the crankcase area. 

red lawn mower

You can also use a drain oil plug or vacuum cleaner with the hose attachment to drain excess oil surrounding the area. Properly dispose of excess oil. 

Step #2: Drain All the Oil

Next, you’ll need to drain all the oil from your lawn mower. You can do this by tilting the lawn mower on its side, making sure that the carburetor is facing upwards. 

The next step is to remove the oil cap or dipstick. Also unscrew the oil tube to ensure that all the remaining oil is released.

removing excess oil in lawn mower

Once you drain oil from the container, replace the oil cap or dipstick and dispose of the used oil properly. 

Step #3: Check for Excess Oil Left

Next, you’ll want to check for any excess oil that may have spilled. Use a clean rag or paper towel to drain excess oil and then dispose of it.

Once you’ve drained all the oil from your lawn mower, you’ll need to add the correct amount. I always check my lawn mower’s owner’s manual to determine how much oil it takes.

How to Avoid Overfill of Your Lawn Mower Engine

To avoid overfilling your equipment’s engine, follow the recommended oil needed found in your owner’s manual carefully.

Additionally, use the right type and viscosity of oil [1] for your mower to avoid further engine damage and extend the its lifespan. 

lawn mower overfilled with oil

You should also avoid spilling oil when filling up or topping off your mower, and always check the oil level after each use to make sure it’s not too high.

It’s essential to follow proper safety procedures for lawn maintenance and care. So if you notice any issues with your lawn mower or engine, such as leaking oil or overheating, it’s best to take it to a repair shop for professional assistance.

Engine oil is key to ensuring that your mower runs efficiently, so avoid placing too much oil. 


Will too much oil prevent a lawn mower from starting?

If there is too much oil in your equipment’s engine, it may be difficult or impossible to start. Moreover, excess oil can cause the engine to produce more heat and become damaged.

In general, however, adding too much oil to its engine may cause it not to run well and experience damaging effects such as overheating or seal damage. 

How much oil can a lawn mower take?

The amount of oil a lawn mower can take will depend on the model and manufacturer.

If you’re unsure what kind of oil to use and how much you should put in, I highly recommend asking a professional for help. Also, check your manufacturer’s manual to find out the recommended motor oil level. 


Placing too much oil in a lawn mower could be a disaster for your equipment and may cause your lawn mower failing to start. Filling your tank with more oil than needed not only damages your machine’s engine but also other crucial components. 

However, you can finally avoid overfilling your mower engine and ensure optimal performance with these valuable tips.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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