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5w30 vs 10w30 Lawn Mower Oil

By: Leon Rhodes

Manufacturers recommend using SAE 30 oil in their older lawnmowers, however, you can use 5w30 and 10w30 oil without problem. The difference between 5w30, 10w30 and SAE 30 oil is how well they flow when cold. When hot all three oils provide the same viscosity rating(30).

5w30 vs 10w30 Honda Lawn Mower Oil

5W30 oil can be used in lawn mowers that recommend using "SAE 30" oil. This is because 5w30 and SAE 30 oil provide the same protection once the engine is hot. They flow at the same rate and offer the same amount of small engine friction(heat) protection after they warm up.

10W30 oil can be also be used in lawn mowers because it provides the same protection as SAE 30 oil. As long as the number after the w in your oil type is 30 the oil will provide the same amount of protection as an SAE 30 oil. Oil technology has improved over the years.

Which Lawn Mower Oil To Use

The best oil to use in a lawnmower is always the one recommended by the manufacturer, which is typically SAE 30. Companies like Honda also have a house brand oil to use in their lawn mowers. If you don't have a Honda mower manual, or you don't have the recommended oil, you can use 5w30 and/or 10w30 as a safe substitute for SAE 30 oil.

You don't have to use SAE 30 or house brand oil in a lawn mower, in fact you can probably save money with a cheaper but just as effective alternative. The reason companies offer their own brand of oil for their mowers, besides profit, is to control oil quality. Advancements in oil technology have mostly taken care of that problem.

SAE 30 is not the same as 10W30. SAE 30 is a single viscosity oil meaning it flows more slowly in a cold engine. 5w30 and 10w30 oil are multi-viscosity oils, they flow better in a cold engine and provide the same protection as SAE 30 oil when hot.

I use 5w30 synthetic oil in my Honda lawnmower and have never had any problems. Fun fact: Making sure you regularly change your mower oil is often more important than the oil you use.

Lawn Mower Oil Thickness

SAE 30 is thicker than 10W30 until it warms up. This means a cold start with SAE 30 is slightly harder than a cold start with 10w30 and the engine is less protected during the warm-up period. Engine oil that flows more freely can coat and protect engine components better when they are still cold, thus reducing wear and tear on your mower engine.

Honda recommends synthetic oil in their lawn mower engines but not until a new engine has had at least 5 hours of use. Enough wear to properly seat the valves is required before switching from regular oil to synthetic oil.

The Difference Between Oils

The difference between SAE 30 oil and 5w30 oil is that 5w30 oil will flow better and better protect your mower engine when cold. As the engine warms up the 5w30 oil will thicken to provide more protection. Once hot both oils will provide a 30 viscosity protection rating.

You can use 5w30 instead of SAE 30 oil in mower engines but not 5w20(or less). The number after the w is the important number and since Honda recommends SAE 30 you want to make sure not to use anything less than 30. Engine damage can happen if you do.

If you put car oil in a lawn mower nothing bad will happen as long as you make sure the viscosity rating is high enough, which means at least 30. SAE 30 or any oil rated 'w30' should be OK.

Can you use regular motor oil in a lawn mower?

SAE 30 oil is recommended, however, 5w-30 and 10w-30 will work in lawn mowers and other small engines. The important thing to remember is the 30 in the oil type, it represents the operating temperature viscosity required by the engine.

Is SAE 30 the same as 10W30?

Not entirely. SAE 30 oil has a 30 viscosity rating when the engine is cold and so it may flow a little more slowly at first. 10w30 starts with a 10 viscosity rating when cold and gradually becomes 30 viscosity as it heats up.

Can I just add oil to my lawn mower?

If your lawn mower is low on oil and you don't have time to give it a proper oil change then yes, adding fresh oil before using the lawn mower is a good idea as it may prevent engine damage. Just remember to change the oil and give your lawn mower a tuneup soon after.

When should I change my lawn mower oil?

Most lawn mower manufacturers recommend changing the oil at least once per season or for every 50 hours of operation, whichever is less. Clean oil is perhaps the most important factor in making your lawn mower last, followed closely by sharpening the blades and changing the air filter.

Should I run my lawn mower before changing the oil?

Yes, running the mower engine to bring it up to operating temperature, which typically takes 15 minutes, is a good idea before changing the oil. Warm circulated oil will drain better and remove contaminents that would otherwise sit in the engine.

What's the difference between 5w30 and 10w30 oil?

The difference is how well they flow at startup when the engine is still relatively cold. This means both oils will have the same viscosity rating when hot but the 5w oil will flow more easily when cold.

Source: I have Over 35 years of experience with small engines, LR. Always consult your lawn mower manual for recommended maintenance instructions.

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