Too Much Oil in the Lawnmower? Symptoms + What to DO

Are you concerned that there’s too much oil in your lawnmower? Read on, these are the symptoms of too much oil in a mower.


Symptoms of Too Much Oil in Lawn Mower

Too Much Oil in Mower Symptoms

There is no problem with leaving the oil fill cap off until your next oil change. But if you spill excess motor oil on the mower deck or ground it will eventually return to the air as volatile organic compounds (VOCs). If you leave an excessive amount of motor oil in the lawnmower, it can eventually overheat and cause other problems.

Here are the most common problems caused by overfilling a lawnmower with oil:

Oil Cooling System Overheating

Oil is used as a coolant for most small engines. If the oil is not consumed during operation or spills out onto the ground it can become very hot. When this happens, it will start to evaporate and with high enough temperatures it can create hazardous air pollution. The oil fumes have been linked to asthma and cancer in humans. In extreme cases, the engine will overheat and even catch fire.

Mower Engine Misfires

If too much oil is left in the lawnmower or oil is spilled on the mower or lawn it can lead to misfires. The oil will build up in the air filter and block air flow. If too much oil accumulates, the spark plug may fail, starting a fire.

Oil Spills

When you refill the mower with motor oil, never fill it beyond the maximum indicator. If you do, oil can spill on to hot engine components or the ground. When the mower is started it will start to vaporize and fumes from evaporating oil will be released into the air as well as oil that has seeped into the ground.

Mower Engine Loses Power

The excess lubrication properties of motor oil are needed when the engine is running. If too much oil is in the mower there won’t be enough for lubrication and buildup on the cylinder walls will cause a loss in compression. This can lead to reduced power, inefficiency in fuel usage, poor bagging performance and reduced cutting speed.

Mower Engine Seizes or Stalls

Too much oil in the lawnmower can cause the piston rings to stick and seize up or stall. Too much oil also decreases compression, which can lead to a loss of power and difficult starts.

Conclusion:  Too Much of a Good Thing

Lawnmower engines are air-cooled, so if there’s too much oil in the crankcase, it can harm it’s ability to cool the engine (lawnmowers do overheat).  While it’s not as serious as running the mower out of oil, you should drain out the excess oil before running the engine.

You can always go electric.  When comparing an electric vs. gas lawnmower, the electric looks like a better option every year if your lawn is under half an acre.