Pinning down the differences between types of motor oil can get kind of exhausting if you don’t have a good system to do it. In general, oil is categorized based on how thick, or viscous, it is. Both thickness and viscosity refer to the ability of a liquid to flow. Oils or other liquids that have a greater thickness or viscosity will also have a greater resistance to flowing. With this in mind, let’s get into the engine oil comparison of SAE 30 vs 20w50.
SAE 30 vs 20w50 (The Short Version)
The general difference when it comes to SAE 30 vs 20w50 is that SAE 30 is much thinner than 20w50 when hot. On the other hand, when cold (winter temperatures), 20w50 will be thinner than SAE 30 oil. This is because SAE 30 is a single-grade oil and 20w50 is a multi-grade oil with additives that allow it to maintain a low viscosity when cooled.
Is SAE 30 the Same as 20w50?
As I was getting at in the above section, no, SAE 30 is not the same as 20w50. They are actually very different types of motor oil. The biggest difference is that SAE 30 is only rated for its viscosity one time while hot. This is because SAE 30 is only intended for use in engines that don’t need to start in the cold. 20w50 is a multi-grade oil which means that its thickness is rated once while hot and once while cold.
The Society of Automotive Engineers (SAE) uses a standardized scale from 0 to 60 to rate motor oils based on their viscosity. Lower numbers represent lower viscosities, and higher numbers represent greater viscosities. The “w” in 20w50 is for a winter or cold weather rating. So, 20w50 has a viscosity grade of 20 when cold, and 50 when hot. SAE 30 is only rated at a viscosity of 30 when hot.
The Characteristics of SAE 30 and Its Benefits
One of the most widely known characteristics of SAE 30 is that it is the go-to small engine oil. SAE 30 has a viscosity that sits right in the middle of the thickness scale and it’s usually found in the engines of lawn mowers, trimmers, and other equipment used exclusively during the warm seasons.
Though it has a handful of benefits, the main perk of using SAE 30 is that it lubricates small engines effectively and lasts a long time. When it comes to something like a lawn mower’s engine, multi-grade oils aren’t necessary. Additionally, SAE 30 is really easy to find and can be used in other tools with small gas engines.
The Characteristics of 20w50 and Its Benefits
When it comes to an oil like 20w50, there are a handful of specific uses. This is an engine oil that is quite thick and can handle very hot operating temperatures without breaking down. Because of this, you’ll find 20w50 used in large gas or diesel engines like those in cars, motorcycles, or aircraft.
Another reason that 20w50 is used in larger vehicles is because it’s a multi-grade oil. This allows it to perform well at a wider range of temperatures. With a cold viscosity of 20, this oil will remain relatively thin and does a better job of lubricating an engine in freezing temperatures compared to SAE 30. Since 20w50 has a greater thickness when hot, it is a good sealant and provides a lot of cushioning for hardworking engines.
However, if you put 20w50 into the wrong type of engine you’ll end up putting a ton of extra stress on the motor. As far as a lawn mower engine goes, I’ve never heard of 20w50 being recommended by any manufacturer.
Frequently Asked Questions About These Oils
I’ve tried to describe all the differences between SAE 30 vs 20w50, but I have come across a couple of questions that a lot of people tend to ask. Just in case I missed something or you have any doubts, I’ll get straight to the point below.
Can I Use 20w50 Oil in My Lawn Mower?
No, I would never recommend using 20w50 oil in your lawn mower. Almost all lawn mowers require an oil that has a viscosity rated at 30 when hot. Putting in an oil with a rating of 50 would be really bad for the engine.
Lawn mower engines simply don’t generate enough power to need an ultra-thick oil. Also, it’s usually unnecessary to use multi-grade oil in general when it comes to lawn mowers. Since grass doesn’t grow in freezing conditions, you probably won’t need an engine oil that can operate in the cold.
Is SAE 30 Thicker Than 20w50?
As far as viscosity goes, SAE 30 is not thicker than 20w50 when hot, but it is thicker than 20w50 when cold. Since it is a multi-grade oil, 20w50 has additives in it that allow it to remain thin (at a viscosity of 20 to be exact) when cooled.
SAE 30 does not have any additives because it is a single-grade oil and it isn’t rated for cold temperatures. But, when single-grade oil is cooled, it becomes even thicker than usual. So at cold temperatures, SAE 30 will be much thicker than 20w50. At a very viscous state, using SAE 30 in engines that need to start in freezing climates is not good for your engine.
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