Is Lawn Mower Oil The Same As Car Oil?

Blog/ July 8, 2019

For a lawn mower to function correctly, it must remain in top condition – and it also needs its fuel. That means that changing the oil is a basic maintenance task that you need to do regularly, for the sake of its durability as well as the long term health of your lawn.

The good news is that oil changes are easy to do, and it will have many benefits for your mower because it helps it operate smoother. This is because oil tends to carry the carbon and ash that the combustion process creates in the engine as you use the mower – which is why the oil becomes darker as you use it. However, the oil change does not mean you use any kind of oil in the engine, which raises the question – is motor oil safe to use in a lawn mower engine?

Note: Before you change the oil though, you need to check your operator’s manual. This will help you know the oil type and grade you need to put in your machine and ensure its smooth operation.

Factors to consider when choosing an oil for the engine

There are a number of factors you need to consider when selecting an oil grade to use in the engine, with the most important one being the oil viscosity, which will ultimately determine the levels of lubrication within your engine, and its running efficiency.

Here are some of these considerations.

Viscosity

There are two viscosities that a lawn mower engine will use – the SAE 10W-30 when the weather is cold, and SAE 30 when the weather is warm or hot.

The SAE, which means the Society of Automotive Engineers, has various grading of oil that are useful to different engines. For a lawn mower, their SAE 30 is the best option. It is a single grade oil, hose structure fits a small engine that uses air to cool it while it operates. These engines include chainsaws, tractors and lawnmowers.

On the other hand, the SAE 10W-30 is a single grade oil as well, but the engine can utilize it even when the temperatures are low. The W means winter.

Two-stroke oil

If the mower has an engine that is of the two-stroke kind, this means that the process of internal combustion completes a whole power cycle. That means that one revolution of the crankshaft must have two movements of the piston in the engine. In a case like this, you will need an oil that is of the two-stroke variety.

In case you are not sure what type of engine you have, the manual of the lawnmower will explain it comprehensively, so that you can choose the right oil.

There is something you must note though: if your engine is a two-stroke type, avoid regular automotive oil entirely. This is due to the presence of additives and detergents in regular automotive oil, which will make the two-stroke system wear down very quickly. Always go for oil that has any of these labels: SJ, SG, SF, and SH, as they denote the performance rating of the oil as tested by the American Petroleum Institute (API).

Whether the oil has additives

You can become easily confused when you go to an automotive store and check out the selection on the shelves, especially when you see the additive section. While they might seem tempting to add to your oil, do not succumb to that temptation – especially because you are using lawnmower oil.

The engine of a mower is small, while the additives will only be good for a large engine. However, there is an exception to the rule: if the oil you use contains ethanol, then you should use a gas additive. This is because ethanol in gas will lead to failure of a small engine, due to the corrosion it causes on the inner parts.

Can you use a generic oil or must you go for the branded ones?

The usual scenario is that you will see the top brands advertising their oils. However, you do not need to buy all these brands, or any specific one. Even the generic oils can work – but you must ensure they can be used in a lawn mower engine. The advantage with the generic ones is their lower prices, which can save you money in the long term.

What about synthetic oils?

Synthetic oils in a lawnmower engine are fine. In particular, these work very well when the temperatures are extremely cold or hot, because they will give better starting mechanism and the consumption rate of the oil is far less.

What about if I want to use automotive oil?

Using car oil is not the safest option, as the factors you need to consider when buying a mower oil are different from the other oils you find on the market. However, sometimes you may find it difficult to buy mower oil, especially the premium brands since they are very costly, so you can purchase car oil that is the safest bet for your engine – again, not all car oils will work. The usual cases for the best car oils to use are either 10W-40 or 10W-30.

When should you change the oil?

Changing the oil is all a part of engine maintenance and making sure your engine runs smoothly for as long as possible. The manual will indicate the best times to change the oil, although you can adjust it according to the environment you use the mower in.

It usually takes 25 hours of use before you need to change the oil, but if you operate in an environment with high dust levels – then this changing should be more frequent. If you do not have the manual, then change the oil in the early weeks of spring (such as early March), as this is shortly before the next season of mowing.

In fact, this is the longest time you should go between changes – any period longer than that, and the engine will experience issues with its efficiency due to carbon present in the oil.

Final thoughts

Using car oil in your mower engine is not entirely a bad thing. However, you need to be careful about the specific oil you go for, and make sure it works well with the engine you have.