The correct amount of engine oil in a mower is important; too little or too much can be fatal, and both will void your manufacturer’s warranty.
So how much oil does a lawnmower take? Most walk-behind mower engines like Briggs and Stratton will take from empty approximately .65 us quarts (.6lt); Honda walk-behind mowers will take a little less .58 us quarts (.55lts).
If your mower is a tractor mower, check out (internal link) “Can I use 10W30 in my mower?”.
For exact specs, see:
Briggs and Stratton push mower engines
Briggs and Stratton tractor mower engines
This post should have you covered. If you need video help, check out “Checking mower engine oil video” and “Mower engine tune-up video”. The videos walk you through the process of checking, topping up, and changing your mower engine oil.
What Oil Type?
Oil type recommendations will vary between makes, and you should, of course, use the oil type specified. While your mower may be branded Cub Cadet, Toro, etc., it may well be fitted with a Honda, Briggs & Stratton, Kohler, or some other engine make.
The engine maker will be marked on the cover. Mostly, oil type is dependent upon outside temperatures, as this changes the viscosity (resistance to flow) of oil. Modern engines will use a multi-grade such as 10W30 and older engines SAE30.
Single Grade Oil
Single-weight oil such as SAE30 has a good working range (40 to 100 deg F) and is fine for older engines. I prefer to use multi-grade oils, they offer greater protection from temperature swings, and modern engines are designed to use them. If you’re using any four-stroke engine in colder temperatures, you will need multi-grade oil.
Multi Grade Oil
Multi-grade is best for modern engines. This oil was developed to help better protect engines within a larger temperature swing range before their development. Car owners would have to change their oil to a lighter grade oil for winter use—Multigrade, so-called as they are blended oils.
Take, for example, the grade 10W30. The 10W part relates to the grade of winter oil in the blend, and the 30 part relates to the protection offered at hotter temperatures. The resistance to flow rate is tested and graded at 0 degrees F and at 212 degrees F.
If you need lawnmower engine oil check out the Amazon link below.Amazon Lawnmower Engine Oil
Part synthetic and full synthetic oils will offer the very best protection. However, they are expensive. Another great advantage to modern blended oils – the detergent component in the oil actually cleans and breaks down combustion-related contaminates inside the engine.
These contaminants turn into a black sludge, aka Black death, which loves to eat away at the metal and clog up vital oil passages. Use only quality oils. Otherwise, you may void your warranty. Look for the seal of API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d’Automobiles).
The style of dipsticks varies. However, they all operate on the same idea of an upper mark and a lower mark. These marks can be holes, lines, hatched areas, etc. When the oil level is between these two marks, it’s okay, but aim to have it at the upper mark. If your oil level is high and your engine is smoky, you need to check out “Leaking gas from air filter”.
If you need to add oil, add in small amounts and allow it to settle before rechecking. If you’ve too much oil, drain some off and recheck. Too much oil will cause the mower to blow white smoke.
Remember to disable your mower and turn the fuel off before turning your mower over to remove oil. A much better option to drain the oil is to use an oil/gas siphon. It’s a real time saver, it’s clean, and it’s easy. Just drain the oil out through the dipstick tube.
You’ll find a link to the oil siphon I use here on the “Small engine repair tools page”. It works best if the engine was running a while first, just long enough to warm the oil, helping it move more freely.
Checking Engine Oil Level & Adding Oil
1 Level – The mower should be cold and on level ground. If your mower has already been running, just allow the oil to settle for five minutes before checking.
2 Locate – Locate the dipstick. Usually, they are positioned on the side of the engine. The dipstick itself will be marked with an oil symbol or can be brightly colored.
3 Dipstick – Dipsticks come in different styles, but all do the same job. A lower mark (L) and an upper mark (F). When the oil level is in the hatched area, it’s OK. But aim to have it at the F mark.
4 Low Oil – This oil level is way too low. It’s below the low oil level mark indicated here by the lower hole.
5 Add Oil – Add oil in small amounts, and this will prevent overfilling. Let the oil settle before checking.
6 Oil Ok – This is the correct level for oil. Check the oil with every refueling.
7 Too Full – Too much oil here; it’s way above the top hole (Full mark). This can damage the engine and cause oil leaks and white smoke. If the oil level is very full, it will stall the engine. We’ll need to remove some.
Why Check The Oil?
Because the correct quantity and quality of the oil are critically important to the life of the engine, some mowers are fitted with a safety switch that won’t allow the mower to start if the oil level is low. It’s a fantastic idea; lots of otherwise good engines are lost due to a lack of oil.
Unfortunately, not all mowers have this feature, so it’s important to check your oil regularly; an easy way to remember…. check the oil every time you fill the gas tank. An incorrect oil level can damage your engine beyond economic repair. An oil level that’s too low causes excessive heat, friction, and premature wear or complete seizure of the engine.
An oil level that’s too high can:
- Cause engine to smoke
- Cause no start
- Aerate the oil – reducing its ability to cool and lubricate
Lawnmower engines that don’t have an oil filter generally don’t have an oil pump. This means they employ the splash method of lubrication. An overfull oil level can be especially harmful to these engines.
When to Change The Oil?
Change your oil once per season or every 50 hours of operation. Oil needs to be changed as it gets contaminated and diluted by fuel and other deposits associated with combustion and metal friction. If neglected, this oil turns into a diluted sludge which offers little protection to the engine.
Changing the oil is an easy job. Only basic tools are required. Some of the latest generation Briggs and Stratton engines won’t need an oil change ever; they’re designed to run clean. Mmmm….. I think I’d change the oil; old habits die hard. Check out “Lawn mower tune-up”.
Can you put too much oil in a lawnmower? Too much oil in a lawnmower engine can cause white smoke, and oil leaks, and in some cases, the engine won’t start. The fix is simple, drain out the excess oil.
Can you use car oil in a lawnmower? Car engine oil types such as 5w30 or 10w30 are OK to use in lawn mower engines.
- About the Author
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John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.