It’s time to refill the oil in your lawn mower. This can be a scary task to take on if you don’t know which oil goes with which lawn mower. So, what kind of oil does a lawn mower take anyway?
For a 4-cycle engine, use SAE 30 or SAE 10W-30 oil, and for a 2-cycle engine, use SAE 30. These are the typical recommendations, but your owner’s manual will have some recommendations as well. You can tell the difference between the two engines because 4-cycles will have dipsticks and oil filters.
In this content you’ll learn:
A Quick Explanation Of Oil Labels
If you have ever picked up a can of oil, you may have noticed the specifications noted on the label. These can be things such as SAE 15W-30 or SAE 30.
Now, what do these mean?
SAE (Society of Automotive Engineers)
Whenever you see SAE on an oil label, this is a good thing. SAE stands for the Society of Automotive Engineers. They set the standards that oils have to follow if they’re going to have SAE on their label.
The Numbers
The numbers on oil labels refer to the viscosity of the oil. Viscosity is how well the oil flows at a certain temperature. If you see two numbers, it’s the same thing, but with a twist.
Usually, two numbers are listed like this: SAE 15W-30 or SAE 10W-30. The first number refers to the oil’s viscosity at lower temperatures. The second number refers to the oil’s viscosity at normal operating temperatures.
You can tell the first number refers to lower temperatures because of the W. It stands for winter and is there to show that the number before it is for lower temperatures. So, the lower the number the thinner the oil.
So, now you know what oil to get, but when should you use it?
When Should I Change The Oil In My Lawn Mower?
2-cycle engines do not require an oil change since the oil is consumed during operation. All you need to do is use the appropriate oil with the correct mix ratio.
4-cycle engines are a little different. Changing their oil depends on how much the lawn mower gets used and what type of lawn mower it is.
Here are our recommendations for when to change the oil:
- Change it at the start of the season
- For a walk-behind lawn mower, change the oil every 50 hours
- For a zero-turn and ride-on lawn mower, change the oil every 100 hours
How Much Oil Do I Need For My Lawn Mower?
Knowing how much oil to use will save you from returning to the store if you’re short a quart or two. Not every lawn mower will take the same amount of oil though. Let’s start with walk-behind lawn mowers.
Walk-Behind Lawn Mowers
Walk-behind lawn mowers (push or self-propelled lawn mowers) usually take 15 ounces or 18 ounces of oil. That’s great news for saving money on oil!
Now, onto riding lawn mowers.
Riding Lawn Mowers
Riding lawn mowers (zero-turn, rear-engine, or lawn tractors) will take either 48 ounces or 64 ounces of oil. Not so great for those looking to save money, but it’s worth it to keep those powerful machines in tip-top shape.
What Engine Does My Lawn Mower Have?
You must distinguish if your lawn mower has a 2-cycle or a 4-cycle engine. This is because in a 2-cycle oil is added to the fuel through a separate reservoir or the mix has to be done by hand. A 4-cycle uses oil stored in the sump.
You can tell which engine you have by checking your owner’s manual or looking for a dipstick and oil filter. Only 4-cycle engines will have dipsticks and oil filters. There’s also how the engines use the oil too.
How Does a 2-Cycle Engine Use Oil?
A 2-cycle engine, also called a 2-stroke engine, combines the oil with the fuel. Because of this, the oil is burned up at the same rate as the fuel. This means that new oil needs to be added when refilling fuel and oil changes aren’t necessary because no oil is stored in the engine.
What Kind Of Oil Does A 2-Cycle Engine Use?
There is a range of oil you can use in a 2-cycle depending on the age of the engine. SAE 30 is usually the manufacturer’s recommendation for modern engines. SAE 40 is recommended if you have an extremely old engine. When buying these oils, make sure the oil container mentions it’s designed for 2-cycle or 2-cycle engines.
What about 4-cycles though? How do they use oil and what oil do they take?
How Does a 4-Cycle Use Oil?
A 4-cycle engine, also called a 4-stroke engine, keeps oil inside the oil sump and reuses it when the engine is turned on. The oil inside 4-cycle engines needs to be regularly checked because it slowly burns away over time. A 4-cycle engine will require oil and oil filter changes.
What Kind Of Oil Does A 4-Cycle Engine Use?
Most manufacturers recommend SAE 30 for 4-cycle engines. This oil is ideal for small engines in warmer environments. However, if you happen to be in a cooler region, you may want to consider using SAE 10W-30.
What Happens If I Mix Up The Oils?
Both types of oil are designed to lubricate the engine to keep the parts moving freely. However, using 4-cycle oil on a 2-cycle engine or vice versa will cause problems. This is because 2-cycle oil is designed to combust in fuel and 4-cycle oil isn’t.
So, what will happen?
Using 4-Cycle Oil in a 2-Cycle Engine
4-cycle oil added to a 2-cycle engine will very quickly, if not immediately, cause the following problems:
- Foul the spark plug
- Clog the exhaust port
- Degrade the engine
- Cause significant smoke
- Stop the engine from starting
Using 2-Cycle Oil in a 4-Cycle Engine
Adding 2-cycle oil to a 4-cycle engine does not have the same effect as the other way around. In this case, the engine will start to degrade.
So, let’s say you get the correct oil for the correct engine, which we’re sure you will.
What do you do?
How Do I Change The Oil In A Lawn Mower?
Since 2-cycle engines don’t need oil changes, the below processes are only for 4-cycles. The size of your lawn mower will also determine what to do. For example, small lawn mowers can be tipped over, whereas large lawn mowers cannot.
Let’s start with small lawn mowers.
Changing The Oil In A Small 4-Cycle Lawn Mower
So, small lawn mowers are designed to be tilted over and have the oil poured out. It is very important to know which way you can tilt your mower. The direction will depend on the manufacture and design of the lawn mower engine.
Check which way you need to tilt the lawn mower by referring to your manufacturer’s recommendations. Tilting the mower in the wrong direction can leak oil into the carburetor or air filter.
Steps To Change The Oil In A Small 4-Cycle Lawn Mower
There are two stages to this process. Stage 1 is removing the old oil and filter. Here are the steps:
- Remove the oil filler cap/dipstick.
- Tilt the lawn mower over.
- Place the oil pan (container to collect old oil) to catch the oil.
- Remove the oil filter (if your lawn mower has one)
- Allow the old oil to fully drain.
- Last, dispose of the oil.
Next, there’s stage 2, which is installing the new oil and filter. Here are the steps:
- Place the lawn mower in an upright position.
- Install the new oil filter (if required).
- Add the new oil by pouring in approximately 3/4 of the required amount.
- Check the oil level with the dipstick to see if the level is at the “full cold” mark.
- Add more oil as needed.
- Put the oil filler cap/dipstick back into place.
- Clean off any spilled oil from the lawn mower.
- Start the lawn mower and let it run for a few minutes to make sure everything is working properly.
- Rest the engine until it’s cool.
- Check the oil level again (the oil filter may have filled, reducing the level on the dipstick).
- Last, add more oil as needed and test the lawn mower again.
Changing The Oil In A Large 4-Cycle Lawn Mower
Large lawn mowers are too big to be tilted. There is no way that you will be able to tip a big zero-turn mower on its side. Manufacturers know this, so they have a different way to change the oil.
Steps To Change The Oil In A Large 4-Cycle Lawn Mower
There are two stages to this process too. Here are the steps for stage 1:
- Locate the oil drain plug on the sump.
- Place the oil pan (container to collect old oil) to catch the oil.
- Remove the drain plug.
- Remove the oil filler cap/dipstick for increased flow.
- Remove the oil filter.
- Allow the old oil to fully drain.
- Last, dispose of the oil.
The steps for stage 2 are:
- Install the oil draining plug on the sump.
- Install the new oil filter.
- Add the new oil by pouring in approximately 3/4 of the required amount.
- Check the oil level with the dipstick to see if the level is at the “full cold” mark.
- Add more oil as needed.
- Put the oil filler cap/dipstick back into place.
- Clean off any spilled oil from the lawn mower.
- Start the lawn mower and let it run for a few minutes to make sure everything is working properly.
- Rest the engine until it’s cool.
- Check the oil level again (the oil filter may have filled, reducing the level on the dipstick).
- Last, add more oil as needed and test the lawn mower again.
Conclusion: What Kind Of Oil Does A Lawn Mower Take?
Now you know what kind of oil a lawn mower takes. You could even share your new insights and skills to help out your friends and neighbors! In short, remember 2-cycle SAE 30 oil for 2-cycle engines and 4-cycle SAE 30 or SAE 10W30 for 4-cycle engines.
Unfortunately, there are still many more confusing parts of lawn mower maintenance to cover. So, care to help us out with some tips or stories about your experiences with lawn mower care? Let us know in the comments below!
We’ll start with this tip on putting a lawn mower tire back on the rim. You never know when you’ll need to do so!
