What Is The Best Oil For A 4-Stroke Mower?

Choosing the correct oil can make a huge difference in how your 4-stroke lawn mower runs, but you aren’t sure what is the best oil to use. Don’t worry! You are on the right page, and we are here to help. We did the research, and here’s what we found.

The best oil for use in 4-stroke lawn mowers is grade SAE 30. The synthetic variations, SAE 5W-30 and SAE 10W-30 can also be used for improved engine performance and longer serviceability life.

Using the correct oil is crucial for the lawn mower’s performance and long serviceability life. It ensures that the equipment runs at its best. In this post, we will dig deep into what makes the best oil type and brand under certain conditions. We will also discuss the consequences of using the incorrect engine oil type. Let's begin!

Illustrative Editorial” image of the serial number of genuine Honda umr435t which was made in Thailand, in white studio. - What Is The Best Oil For A 4-Stroke Mower?

Why Choose The Best Oil For 4-Stroke Lawn Mowers?

For homeowners who enjoy caring for their lawns, the lawn mower is their best friend. As such, proper care and maintenance are crucial for the engine to perform effectively. The lawn mower engine should be operated using the correct oil.

Oil is the main ingredient to keep the engine running. The lubricating and cooling capabilities of oil can't be understated. It makes all the moving parts of the combustion engine run smoothly. The engine parts can work at high speeds and even at extreme temperatures.

Filling oil in engine on a lawn mower

However, not all engine oil is formulated to be the same. Each has unique elements and viscosity grades that let the 4-stroke lawn mower run smoothly at certain air temperatures.

Every user must determine what engine oil type meets his mowing and lawn mower's requirements.

Choosing The Best Oil For A 4-Stroke Mowers

Mechanic pouring motor oil to engine with copy space on black background,Double exposure,Automobile repair shop business concept

With the advent of technology, choosing among various engine oil types in the market can be challenging. With the correct oil, it affords prime engine health and longer useful life. Whether you have a walk-behind or a ride-on mower, the following is a helpful guide to knowing the best oil.

Standard Oil

SAE 30 is the standard oil for 4-stroke lawn mowers. Here are its elements:

  • Choose this oil type if you mow in a warm or hot climate, (a temperature range is 40-100 Fahrenheit or 4-38 Celcius). Even if you live in colder regions, you won’t start mowing until the temperature is warm again.
  • Specially formulated for small to mid-size engines. 4-stroke lawn mower engines fall into this category.
  • Best for 4-cycle engines. Nowadays, most lawn mowers in the market are designed with 4-cycle engines, and 2-cycle engines are becoming less common.
  • Highly adaptive since the viscosity doesn’t alter due to its wide operating temperature range. 
  • A non-detergent motor oil, best for small engines. It contains no additives that trap dirt and dissolves oil sludge until the next change oil.
  • Economical and flexible. This is the same standard oil you can use in your car and truck.
  • Commercially available in hardware, automotive shops, DIY shops, and similar establishments, hence, accessibility is not an issue.
  • Endorsed by Briggs and Stratton, the leader in small engines.

Synthetic Oils

Synthetic oils are more refined and afford improved performance and higher protection for the lawn mower engine. The synthetic variations that can be used are SAE 5W-30 and SAE 10W-30.

  • You can use these oil types if you mow in cooler climates.

SAE 10W-30 is thinner oil, perfect for low temperatures below 100 Fahrenheit.

SAE 5W-30 is much thinner, perfect for extremely low temperatures; that is, the best bet for icy climates of up to -20 degrees Fahrenheit.

  • With the same viscosity grade of 30, these are fine substitutes for SAE 30.
  • Artificially blended with chemical compound additives that make them slippery, thus minimizing friction, perfect for providing lubrication in cold weather.
  • Undergoes a rigid process to remove impurities, thus prolonging the serviceability life of the engine. It protects the engine from rigid wear and tear.
  • The only drawback is that it is more expensive.

You might be interested to learn about engine oil at low temperatures.  We have these posts for you:

Can Engine Oil Freeze? and Condensation in Engine Oil - What To Do?

What Are The Recommended Brands of Engine Oils for 4-Stroke Mowers?

Illustrative Editorial” image of the fuel tank cover of Honda umr435t which was made in Thailand, in white studio.

Here are some of the recommended brands of standard oil SAE 30 and its synthetic variations that can be used for 4-stroke lawn mowers:

This is the Husqvarna brand, specially formulated for 4-cycle engines of mowers. It optimizes engine performance and minimizes engine deposits to protect from sludge and varnish. It contains additives to minimize corrosive and mechanical wear.

This SAE 30 for 4-stroke engine oil is available on Amazon. Check it out.

This is the Royal Purple brand which can be bought in 32 ounces in a bottle or can. It affords your lawn mower better protection from corrosion and improved fuel efficiency. It contains antioxidants to prevent oil from degrading at high heat.

This SAE 30 motor oil is available on Amazon. Check it out.

The STP brand of premium small engine oil is recommended for SAE 10W-30. This is specially formulated for use in push mowers and tractors.  It is an all-weather synthetic oil that can be used both for cold and warm climates. Not only during operation but also storage between mowing seasons, your machine is protected from corrosion by keeping the engine components clean. This brand is packaged in 32 fluid ounces in cans.

This STP 4-cycle oil is available on Amazon. Check it out.

The Briggs and Stratton brand SAE 5W-30 is a fully synthetic oil that is perfect for extremely cold temperatures. Your mower can operate smoothly on wet grass and withstand slippery and rough terrain. Though relatively expensive, this brand has earned exceptional product reviews from its users.

This Briggs & Stratton 5W-30 is available on Amazon. Check it out.

Understanding Engine Oil Codes

Motor oil pouring

When you shop for engine oil for your 4-stroke lawn mower, aside from the different brands, don’t be daunted by the various numbers and codes printed on the bottle label. Each code explains how well the oil performs in different weather conditions. The outdoor temperature has a direct impact on engine oil viscosity or weight. Viscosity measures the thickness or consistency of oil during specific air temperatures.

The Society of Automotive Engineers (SAE) sets the industry standards for engine oil types. The numbers displayed on the packaging label mean the oil's viscosity,  ranging from 0 to 60. Higher numbers mean high or hot temperatures. The higher the number, oil becomes less viscous or lighter. Therefore, higher numbers are used for warm weather. At low or cold temperatures, oil viscosity increases, or oil gets thicker and heavier. Hence, low numbers work for the cold weather.

To illustrate, SAE 30 is a monograde oil since it displays one viscosity grade of 30. This is rated for hot viscosity. This explains why it is limited to use in warm temperatures only.

The synthetic versions, SAE 5W-30 and SAE 10W-30, are multigrade oils since they contain two numbers, separated by ‘W,’ which stands for ‘winter.’ The preceding number means viscosity at low temperature, while the number after W translates to viscosity at high temperature.

Multigrade oils, in contrast to SAE 30, have a wider temperature tolerance. This explains why they can be used in extreme temperatures.

For example, a lower number after W, such as W20, isn’t a good choice because it is very thin and cannot properly lubricate. This can cause engine overheating.

In SAE 5W-30, the grade is much lower before W, perfect for cold temperatures. This explains why this grade is used for extremely cold or icy climates.

Learn more about engine oil types in this post:

Can You Put 5W20 Oil In A 5W30 Engine?

What Happens If Incorrect Engine Oil Type Is Used?

You can't just use any oil in your lawn mower, so ensure you're using the recommended engine oil in your machine. Using the incorrect oil type may damage the mechanical parts of your 4-stroke lawn mover. At worst, it may damage the engine, which can cause serious issues.

Another serious consequence is that it may put your mowing operation on hold, thus causing more losses and inconveniences.

Here are the effects of using the incorrect engine oil type:

  • less friction on the moving parts that will cause overheating quickly
  • oil leaks due to thin oil; it will just flow freely and drip like water
  • oil lacks stickiness and is unable to trap dirt resulting in more residue
  • undue stress on the moving mechanical parts due to less lubrication
  • faster wear and tear of the engine and the machine as a whole
  • costly repairs to the engine or even the whole equipment

How Much Oil Does A 4-Stroke Mower Take?

The amount of oil needed for a lawn mower engine depends on the size and make of your 4-stroke lawn mower. Generally, you will need between 400-600 ml of engine oil. Ride-on mowers typically need between 1-2 liters of oil. This is the volume of oil that you will need during every oil change.

Just a tip, do not mix old oil and new oil. If there is still unused oil at the crank when you start to have an oil change, you need to discard them before pouring new oil. You must drain the old oil from the engine crank and discard it properly.

If you wish to learn how engine oil is disposed of, this post is worth reading:

Can You Pour Engine Oil Down The Drain?

The Takeaway

The best oil is the correct oil! It is important to use the correct oil for your 4-stroke lawn mower for good lubrication and to function effectively. This way, you will enjoy your lawn care equipment for many more years.

Air temperature and oil viscosity are the two important factors when choosing the best engine oil type. Opt for SAE 30 for warm temperatures. And SAE 5W-30 and 10W-30 for warm and cold climates.

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