The gas filler cap and the oil filler cap might look pretty much the same. It’s pretty easy to get these two mixed up if you’re not paying attention or unfamiliar with the lawn mower. Thankfully, this isn’t too big a deal if you notice straight away and take care of it as soon as possible. So, if you accidentally put gas in the oil filler on your lawn mower, you can follow these steps to get things back to normal.
What Can Happen When You Put Gas in Your Mower’s Oil Tank?
If you don’t run the engine, then not much is actually going to happen if you put gasoline in the oil tank of your lawn mower. But if you fire up your engine, you will run into some issues with lubrication and potentially dangerous gasoline vapors. If the engine gets hot, then the gasoline could vaporize and maybe ignite, causing a bit of a bang.
Also, your lawn mower won’t be lubricated properly, so it’ll overheat and not run right. The best thing to do is remove the contaminated oil and start again fresh.
What You’ll Need to Fix This Issue (Equipment List)
To remove gas mixed with oil in your lawn mower, you’ll need to get hold of a few tools, materials, and a few parts. Here’s a list of things you’ll need for both riding lawn mowers and push mowers that have gas in the oil tank of a lawn mower.
Push Lawn Mower Tools, Material, & Parts List
- Oil Pan
- Cleaning Cloth
- Oil
- Funnel
- Plastic Bag
Riding Lawn Mower Tools, Material, & Parts List
- Oil Pan
- Cleaning Cloth
- Oil
- Oil Filter
- Funnel
- Socket Wrench
How to Remove Gas From Lawn Mower Oil Tank (Step By Step)
Depending on what type of lawn mower you have, you’ll need to follow a different set of steps for each. This is because some lawn mowers are designed to have oil poured out of the filler cap, and some are designed to have oil drained out of the sump. Here are the steps for both methods if you accidentally put gas in the oil tank of your lawn mower.
Push Lawn Mower Oil & Gas Removal
So if you have a push-style mower, then you can follow these 11 steps to get you up and running again if you got gasoline in the oil tank of your lawn mower. Let’s go over a summary of the steps first.
- Position the Oil Pan
- Remove the Oil Filler Cap
- Cap off the Fuel Tank
- Tilt Over the Lawn Mower
- Pour Out the Contaminated Oil
- Allow the Engine to Drain Fully
- Leave the Cap Off for a While
- Fill the Engine with Oil
- Replace the Oil Cap
- Uncap the Fuel tank
- Run the Engine
Position the Oil Pan
The first job is to take your oil pan and position it next to your lawn mower on the same side as the oil filler cap.
Remove the Oil Filler Cap
Next, remove your oil filler cap and set it to one side. Just be careful that it doesn’t pick up any dirt, as the dirt will end up getting into your fresh oil.
Cap Off the Fuel Tank
If you have a gas tank with fuel in it then, you’ll want to cap it off. This is so that when you tip over your lawn mower, the fuel doesn’t leak out. For this step, remove the fuel cap and then lay a plastic bag over the fuel tank opening. Finally, reinstall the gas cap.
Tilt Over the Lawn Mower
With the gas cap sealed, it’s time to tip over the lawn mower. You must make sure that you tip the lawn mower the correct way so that the air filter is pointing up and the filler cap is pointing down. This is so that oil doesn’t pour from the engine and into the carburetor and the oil filter.
Pour Out the Contaminated Oil
Now, as you tip the lawn mower over, the oil will start to pour from the filler cap. So, make sure that you have the oil pan still in position to catch the old oil.
Allow the Engine to Drain Fully
For this step, you’ll want to have some patience. Unlike a regular oil change, you want to make sure you get as close to 100% of the contaminated oil out of your lawn mower. So, you might need to move the lawn mower around a bit to get the last drop of oil out.
Leave the Cap Off for a While
Once the oil has stopped draining, you can upright your lawn mower and let it rest for a while. This is so that any remaining gasoline can evaporate out of the engine. Now, if you wanted to, you could leave your lawn mower with the oil cap off overnight. This should be more than enough time for any remaining gas to disappear.
Fill the Engine with Oil
By this stage, all the oil and fuel will be removed from your lawn mower. So, now it’s time to refill the engine with fresh oil. So, grab the right oil for your lawn mower and pour it into the filler cap using your oil funnel. Just make sure that you fill the oil level to the correct level and that you use the dipstick to check.
Replace the Oil Cap
Next, replace your oil filler cap back onto your lawn mower. Then use a cleaning cloth to clean up any spillage.
Uncap the Fuel tank
With the oil replaced, it’s time to remove the plastic bag from the lawn mower fuel cap. If you forget, you will have problems with the fuel cap ventilation. So, remove the cap, then the plastic bag, and replace the fuel cap.
Run the Engine
Finally, run your lawn mower’s engine to allow the new oil to coat the inside of the engine. Also, you can use this time to test your lawn mower to make sure there aren’t any performance issues. It’s highly unlikely that there will be, but it’s worth checking.
Riding Lawn Mower Oil & Gas Removal
Now that walk-behind lawn mowers are taken care of, let’s look at bigger mowers that can’t be tipped over. Here’s a summary of the steps you’ll need to follow if you have gas in the oil in your lawn mower.
- Position the Oil Pan
- Remove the Bolt from the Sump
- Allow the Engine to Drain Fully
- Remove the Oil Filter
- Install the Bolt into the Sump
- Install a New Oil Filter
- Fill the Engine with Oil
- Replace the Oil Cap
- Run the Engine
Position the Oil Pan
Place an oil pan under your lawn mower’s engine. You’ll want to position the oil pan so that it sits under the drain bolt on the underside of the engine’s sump.
Remove the Bolt from the Sump
Next, use your socket wrench to remove the bolt from the sump of the engine. With some lawn mowers, you might need to use an Allen wrench or some other design tool to remove this bolt.
Allow the Engine to Drain Fully
As soon as you remove the bolt, the oil will begin to drain. So, allow the oil to fully drain until the engine is empty. To speed up the draining process, you can remove the oil filler cap.
Remove the Oil Filter
While the oil is draining, you can go ahead and remove the oil filter from your lawn mower’s engine. Usually, I don’t need any special tools for this other than a cloth towel to get a better grip.
Install the Bolt into the Sump
Once all of the contaminated oil is removed, it’s time to put things back together. So take the sump bolt and install it back into the sump, then tighten it to a snug fit.
Install a New Oil Filter
Next, grab your replacement oil filter and tighten it onto your lawn mower’s engine. I find that wiping some fresh oil on the new filter’s rubber o-ring helps to get a tighter and easier fit.
Fill the Engine with Oil
Following the same steps as a walk behind lawn mower, it’s time to fill the engine with fresh oil. So, make sure you use the right type and the right amount of oil so that the oil level sits within the correct range as shown on the oil dipstick marking.
Replace the Oil Cap
Next, replace the filler cap and wipe up any spillage with a shop rag.
Run the Engine
Now, run your lawn mower for a few minutes, then recheck the oil level. Sometimes you’ll find that lawn mowers with oil filters need the engine to pump the oil to fill the oil filter. If this is the case with your mower, the oil level drops a little during this process. So, allow the engine to cool down, then recheck the dipstick. You might need to add an ounce or two more.
Things to Be Careful Of
There are a few things you’ll want to be careful of when dealing with gas in the oil tank of your lawn mower. Here’s a quick list of things to watch out for.
- Caution when Working Around Flammable Liquids
- Caution when Working Around Hot Engines
- Caution when Disposing of Old Oil
- Caution when Selecting the Correct Oil Type
- Caution Using the Correct Amount of Oil
- Caution when Tilting Over Your Lawn Mower
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