Too Much Oil In Lawn Mower: Effects and Solutions

Adding too much oil to a lawn mower may seem like a fairly inconsequential action. It can, however, be a dangerous practice that can lead to machine-stopping damages. 

Knowing what signs of excess oil to look out for can help you spot the issue before it becomes harder to solve. The main sign of there being too much oil in your lawn mower is the presence of white smoke emanating from the muffler. This, along with some other signs, can indicate that your lawn mower has too much oil.

Keeping your lawn mower moderately oiled is the best way to go. 

Why Use Oil in a Lawn Mower?

Given its consistency, oil is used in machinery as a means of reducing friction across its moving parts. Friction in and amongst machinery can cause damages and stiffness, which may impact performance.

Oil is more commonly needed in older machines due to their age and potential for issues such as rust to impact on performance. One way to avoid this is to keep your mower moderately oiled throughout its lifespan, to reduce the need to add excess oil in the future. 

How to Add Oil to Lawn Mower

Adding oil to your lawn mower is a simple task, best done slowly and steadily to reduce the risk of adding too much. In order to add oil to your lawn mower, you need the following items:

  • Appropriate oil for your lawn mower
  • Oil drain pan or other suitable pan
  • A funnel
  • Rags or towels to clean up any potential spillage

Putting Oil in a Lawn Mower

You should consult your owner’s manual before adding oil, as it will detail the specific steps needed for your particular lawn mower model. Not all lawn mowers are the same, and we can only generalize the following steps. 

  1. Check the amount of oil by using a dipstick. If you find that it is low, it is time for a replacement. When replacing lawn mower oil, make sure to drain the old oil out to help maintain your lawn mower’s performance. 
  2. Drain your lawn mower’s oil. Depending on your type of lawn mower, there are a few ways that this can be done. Some lawn mowers require an extraction tool, whilst others are tipped for the oil to flow out. Larger mowers may also have plugs that can be removed in order for the oil to leak from. 
  3. Make sure that the oil is bled into a container of sorts to ensure it is easy to transport and dispose of. 
  4. Replace the oil by adding new oil whilst your lawn mower is in the correct position.
  5. Use the dipstick to check that the replacement oil is at the correct amount.
oil being funnelled into a lawn mower

Signs of Too Much Oil in a Lawn Mower

There are a few signs to look out for that suggest that there is too much oil in your lawn mower. Too much oil in a lawn mower can be a result of simply mismeasuring the amount that has been added during an oil change, or it may not have fully drained out before adding more oil to the machine.

Hard Start 

Too much oil in a lawn mower can lead to a hard start. You might find it increasingly more difficult even trying to start your lawn mower, due to the lack of friction between parts. Whilst difficulty starting a lawn mower isn’t always a sign that it is broken or over-oiled, it can be used to diagnose the issue if additional effects are noted. 

White Smoke

A lawn mower that has too much oil inside is also likely to produce a white smoke. This white smoke comes directly from the muffler. This is one of the more visible signs that your lawn mower contains too much oil. 

An excess of oil in a lawn mower can also reach the crankcase. This can further prevent start up and will cause the sump pump to overflow. An overflowing sump pump can lead to additional leakages. 

Oil Leaks

Whilst an oil leak from your lawn mower isn’t inherently dangerous, the fact that it is highly flammable should be considered. If your lawn mower is actively leaking oil, or you find excess oil in areas of your lawn mower that it shouldn’t be, make sure that the oil is removed fully and the cause is investigated. 

Oil is highly flammable and can also damage the soil’s pH levels.


An excess of oil in a lawn mower can also lead to constant overheating. Whilst this is not only dangerous due to the flammability of oil, it’s also damaging to the lawn mower’s components. This can be the result of the crankcase being filled or malfunctioning due to the amount of oil present within the mower. Overheating as a result of excess oil may require a full engine scraping to remove it and help return the lawn mower to normal functionality.

Engine Seal Damage

Engine seal damage can come as a result of too much oil being present in the lawn mower. This can lead to additional engine damage and failure, and can lead to more overheating as a result of compartments being damaged or misused. 

How to Remove Excess Oil from a Lawn Mower

You can remove some excess oil from your lawn mower without taking the same steps required when changing oil completely. These methods are best used if there is a slight excess of oil in your lawn mower. If you find that there is an overwhelming amount of oil in your lawn mower and its system, ensure that a full removal and replacement is done instead.

  1. Drain plug of valve port – Unplugging and replugging this plug will help release some oil from your tank. Ensure that you have your dipstick available to recheck levels once the plug has been replaced. 
  2. Oil filter – The oil filter may allow you to drain small amounts of oil at a time.
  3. Oil extractor pump – An oil extractor pump is self explanatory and can be used to remove both small and large amounts of oil from a lawn mower,
  4. Fill hole – Fill holes are often found in lawn mowers that don’t have a drain plug or valve port. Fill holes serve a similar purpose and can be used to remove a small amount of oil.
  5. Turkey baster – If all else fails, a turkey baster can be utilized for removing oil from a lawn mower. These basters work in a similar way to an extractor pump, and are great for removing small amounts of oil at a time. 

How to Prevent Overfilling Oil in a Lawn Mower

Prevention is oftentimes the best method of ensuring that oil isn’t overfilled in your machine. Your engine’s oil capacity should be clearly written out in your lawn mower’s manual, as each and every lawn mower has its own different capacity. These capacities often range from 3/4 of a quart of motor oil to 3 quarts. The larger the lawn mower, the more oil needed.

You can prevent overfilling your lawn mower by only adding small amounts of oil to the machine at a time, and checking its levels with the dipstick. Try to only add 1/2 a quart of oil with each pour until you have reached your lawn mower’s ideal oil level. 

Final Thoughts

Too much oil in a lawn mower engine can lead to immediate issues or deterioration down the line. When refilling your lawn mower’s oil, ensure that just the right amount is used and also make sure that there are no leaks or damages to the oil compartment which could potentially see the oil escape out of.

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