Accidentally Put Gas In Oil Tank Of Lawn Mower? Read This!

Red lawn mower on green grass showcasing its engine and wheels.

Accidents are unavoidable but can be a good lesson. When you put gas in the oil tank of a lawn mower accidentally, many things come to mind. Your lawn mower uses both gas and fresh oil but putting these in the wrong tank can be traumatizing.

Your lawn mower functions like a typical car and gas and oil are a must for it to function optimally.

However, when gas goes into the oil tank, the machine cannot work. This means your lawn will wait a little longer for mowing. Lawn mowers come in different brands and sizes but function almost the same. The mix up does not render your machine obsolete.

All you need is to relax and work on ways to drain the gas from the oil tank.

Here is what happens when you realize the accident.

What Happens When You Put Gas In Oil Tank Of Lawn Mower?

When you put gas in the lawn mower’s oil tank, the machine will not be able to work. These two substances play different roles. Each has to go into its designated tank for it to function optimally. However, the machine needs both and oil to work correctly.

This is a common mistake given the proximity of the two tank openings. It is very easy to accidentally put gas or oil into the wrong tank. However, this is a mistake you can quickly sort without involving an expert.

Your patience will help you get your lawn mower up and running. If you put gas in the oil, the lawn mower will not start. If you put it will the engine is running, it will stop, and this is the first sign that something is wrong in the fuel system. The best thing is not to try and start it.

Doing so might affect other systems, especially in the engine and the entire transmission system.

Most lawn mower transmission systems come fitted with sensors.

These will sense whatever substance you put in and automatically shuts down. This is a defensive mechanism. It protects the engine parts from damages. Gas in the oil tank should not worry you. It is a simple mishap that you can fix at home. All you need are the right tools to help you drain the diluted oil and clean the tank until dry before refilling it.

Below is an easy-to-follow procedure to bring your lawn mower back to life.

What You Should Do When You Put Gas In The Oil Tank Of A Lawn Mower

Lawn mowers come with a tool kit with the right spanners, and yours should not be different. These are the tools you use to open up the tank to drain the mixture. This is because you will have to drain and fill the oil tank several times. This dilutes the oil entirely and will not affect the lawn mower power. This should not take long to achieve.

Below are some of the steps you should take to ensure the machine returns to work in no time.

Disconnect Power From The Mains

Once you realize the mistake, do not try to start the machine. Instead, remove the spark plug and isolate the lead wire. This is the essential protection against shocks, just in case the battery is on. By leaving the spark plug on, you expose the wiring system to shorts when you puncture the wire insulator.

Clean The Oil Drain Plug

Do not take chances when it comes to the plug. Located below the mower deck, the oil drain might store some gas and oil mixture and need to be wiped with a piece of cloth. If required, use elbow grease for cleaning. Cleaning this section is a surefire way of protecting the lawn mower crankcase. Ensure all debris, if any, is cleaned from the drain plug. Gas and oil mixture can easily contaminate the crankcase.

Ensure it is cleaned thoroughly.

Drain The Gas And Oil Mixture

After turning the engine off, the first thing you must do is empty the oil tank completely. Finding the oil drain plug you’d use to remove the old oil during an oil change should be enough to solve this problem. Place an oil pan under the plug and unscrew. Make sure the used oil does not spill. Depending on your lawnmower make; use the right wrench to loosen the nut and use your hand to remove it.

In a perfect world, the oil tank’s liquid would have been completely drained. Even if it seems like any liquid in the oil tank is oil and not gasoline, you should still drain it all because it would have mixed with the gasoline anyhow and is insufficient to start the mower engine. Ensure all the oil successfully drained to the pan before putting back the drain plug.

Do this outside in a well-ventilated area so that toxic gases can escape as well as the the inside of the oil tank can completely dry.

A yellow and black lawn mower left unattended in a lush garden with apple trees in the background.

Replace Drain Plug

Once you are done draining and ensuring everything is in place, replace the drain plug, depending on the kind of mower you have, the kind of oil it uses, and the kind of oil filter your mower uses. Make sure the cap is well placed to avoid any leakages. Given that you will need to add new oil to the oil tank anyway, you can treat this as an opportunity to change your oil, so you might as well do it at the same time.

This will ensure that the new oil your mower will use is supplied with a new oil filter that has not been tainted with gasoline. Confirm with the user manual for the correct oil. This should clear doubts on the best practice to replace the drainage plug.

You need to repeat the draining process several times until there is no gas smell in the gas tank. This should sort you out. However, going forward, make it a habit of checking how clean your lawn oil is before starting the engine.

Apart from accidentally putting gas in the oil tank, you might notice the two mixed somehow. Sometimes the fuel float becomes stuck, leading to gas and oil mixing along the way. This might mean your machine is due for servicing.


Accidentally putting gas in the oil tank is not your lawn mower death sentence. Your lawn mower restored to working optimally after cleaning the system. What’s more, you can do it without an expert’s help, and it does not take much of your resources and time. With the increasing number of lawn mower brands in the market, it is important to note each has its user guide.

Always use this as your reference point when you need to drain oil from the tank. The procedure and tools used might be slightly different. To avoid going through cleaning either the gas or oil tank, ensure each is market correctly. Only use the designated substance to avoid “hurting your lawn mower engine.

Always remember a well-maintained lawn mower lasts longer.

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