Sae 30 vs 15w40: What’re The Differences?

Choosing the right engine oil for your automotive vehicle is a very crucial step that is important for low maintenance cost and long life for engine components.

Earlier we discussed the difference between Sae30 and 5w30 engine oils. This was an in-depth analysis of these two most popular engine oil categories, you can check out it.

Today I’m going to clear every doubt regarding SAE30 Vs.15w40 engine oil.

What are the differences and which one is best for which temperature ranges?

Let’s find out…

But wait…

If you are in hurry then this brief comparison table will definitely save you time to understand these two terms at a glance.

Sae30 Vs 15w40: Similarities And Differences

Sae30 Engine Oil15w40 Engine Oil
1. Sae30 is a hot viscosity-grade oil.15w40 is a cold viscosity grade engine oil.
2. Sae30 is only suitable for hot weather conditions in the operating temperature of 100°C.15W40 is suitable for varying temperature conditions. The word “w” here, indicates winter.
3. Sae30 is a monograde oil. 15w40 is a multigrade oil.
4. It is best to use in some old cars, bikes, lawnmowers, and generator engines.It is best for modern and heavy vehicles such as trucks, loading-unloading vehicles, SUVs, etc.
5. Sae30 doesn’t have detergents.15w40 comes with several useful additives with detergent.
6. Not good to clean dust and debris from the moving parts of the engine.It can clean dust and debris from the engine components.
7. You can not use Sae30 where 15w40 is recommended.You can use 15w40 in place of Sae30.
8. It is either synthetic or mineral oil.It is also available in mineral and synthetic variants.
9. Economic lubricant for old vehicles.A little bit more expensive than Sae30.

15W40 Vs. SAE30: Which One Is Better?

Let me first clear some very basic but important terms so that you can understand them well without getting confused.

What Is SAE30?

SAE (Society Of Automotive Engineers) is an international organization for individual Engineers and its headquarter is in Warrendale, Pennsylvania. It provides different grades to the automobile products such as engine oil, etc, and defines which automobile product is best for use in which conditions.

sae30 engine oil
sae30 engine oil (View On Amazon)

The engine oil viscosity rating is defined between 0 to 60, according to the SAE J300 standard. Low-graded oil seems thinner than high-graded oil. Sae viscosity grade defines engine crankcase and gear oil only.

SAE30 is a monograde oil, which means it has a single viscosity grade. The number “30” in SAE30 defines oil viscosity rating, and how it flows at any particular temperature.

A single-grade oil could be rated either as a warm or as a cold viscosity grade. SAE30 is a hot viscosity grade oil and is commonly used for small engines.

Sae30 Is A Hot Viscosity Oil, What Does It Mean?

The chemical compounds of SAE30 work at high temperatures. This is a hot viscosity oil that is best for using those engines that operates at higher temperatures.

SAE30 engine oil becomes thin at high temperature and provides better lubrication and reduce friction between the different engine moving parts.

Where I Can Use SAE30 Engine Oil?

SAE30 is commonly used for small engines mostly in your lawnmower, snow blower, small tractor, generators, some cars, trucks, etc. Due to the lack of detergent properties, it can also be used in air compressors and hydraulic systems.

For some engines such as air-cooled 4-stroke engines, and small 2-stroke engines, that are operated at high temperatures, you can use SAE30. This is why it is used in some old cars, motorcycles, and stationary gasoline engines.

What Is 15w40?

Unlike Sae30, 15w40 is multigrade engine oil. Where Sae30 is a hot viscosity grade engine oil, 15w40 performs best in varying temperature conditions. Multigrade oils are made of a combination of base mineral oil and some special types of additives. Additives are mixed up in the multigrade oils to boost their performances for various conditions.

15w40 engine oil
15w40 engine oil (View On Amazon)

There are some benefits of using a multigrade engine oil instead of a monograde oil…

  • Provide better engine cleanliness.
  • It disperses very well to the whole area.
  • It protects engine parts from corrosion and from severe wear or tears.
  • It has better thermal-oxidative resistivity.

Sae 15w40 or 15w40 has two parts in its name. The first part 15w describes the flowability of this engine oil at cold temperatures. The engine oil can be used up to -25° Celsius beyond this limit its flowability is lost because it gets thick.

Here, the suffix “W” stands for winter.

The second part 40 indicates that the engine oil is flowable at the operating temperature of 100° celsius.

The Sae 15w40 is functional within the following temperature range

Low-Temperature LimitHigh-Temperature Limit
-25° Celcius100° Celcius

Where Can I Use 15w40 Engine Oil?

As early stated 15w40 is a multigrade oil and can perform better in varying temperature conditions than a monograde oil. It performs best within the temperature range of -25­­° Celcius to 100° Celcius.

Under What Circumstances Is 15w40 Not Usable?

15w40 engine oil is certified to use within the defined temperature range. In harsh winter conditions, it may not thin enough to disperse in the engine.

Must check the compatibility of your automotive vehicle with the 15w40 that is specified by the respective manufacturer.

What Is The Difference Between Sae30 And 15w40 Diesel Oil?

Many people have a very common doubt…

Is The sae30 and 15w40 The Same?

No, both engine oils come with different oil grades. SAE30 is a single-grade oil whereas 15W40 is a double-grade oil.

15W40 is a double grade oil, it means it can be used for low and high temperature. the terms “15W” represent the viscosity of oil in cold temperature and the terms 40 represent the oil viscosity when its operates at high temperature. The engine oil with grade 15w40 can be pumped down to -25° C in the engine.

15w40 remain thick in cold temperature and become thin when the temperature is high. In both the situation it provides better lubrication and protection to engine parts.

SAE30 is only useful to provide lubrication to the engine parts at high temperature (100°C).

Can I Use 15w40 Instead Of Sae30?

The answer is yes, although the oil types have different viscosity grades, it is better to use a multigrade engine oil instead of a single-grade engine oil.

It also depends on which engine type your machine has. if it is a lawnmower, motorcycle, or others. In old machines like lawnmowers, generators, old bikes, etc using Sae30 is fine.

SAE30 Vs. 15w40: Detergent Property

Detergents are chemical additives that mixed up in the engine oil during the manufacturing process. These additives helps to remove the contaminants such as dirt, sludge, vanish, etc from the engine.

SAE30 is not a detergent oil whearas 15W40 is.

15w40 Is Mineral Or Synthetic Oil?

15w40 is manufactured in both varieties. Many brands offer two different types of oil in the category of 15w40. You can choose either their conventional engine oil based on mineral oil or their fully synthetic oils.

The difference is in their pricing. A mineral-based 15w40 will cost you much cheaper than its Synthetic variant. Here, you can see the price advantage in its mineral variant but mineral-based oil has one major disadvantage. Its performance is inferior and unstable in varying temperature conditions than synthetic-based oil.

Can I Mix 15w40 With SAE30?

The chemical composition and the viscosity rating of both the engine oils are totally different. SAE30 is best for those engines that work at high temperature conditions whearas 15W40 is best for both cold and high temperature conditions.

It is advisable to not mix up two different grades oils otherwise, it could impact negatively to the performance of your engine.

Can I Use 15w40 Oil In My Bike?

It totally depends on what type of bike you own and what its manufacturer recommends using as its engine oil. It also depends on the age of your bike. If your bike is old and has covered more than 50k km then 15w40 would be fine but use a higher grade oil in old vehicles because there are chances of oil leakage. Thicker oil works great in this situation.

Can I Use 15w40 In My Lawnmower?

15W40 is a multigrade oil and is not a best choice for your lawnmower. Lownmower has a small engine and using SAE30 for this is advisable. If you pour 15W40 in your lawnmower engine then you can not utilize its multi-grade benefits.

Can I Use 15w40 As Hydraulic Oil?

15w40 is a multigrade oil with high viscosity, on the other hand, hydraulic oil has low viscous properties. If you pour a high viscous oil in place of low viscous oil then it’s perfectly fine.

This is very common to use a multigrade oil like 15w40 in the construction and agriculture machinery in place of hydraulic oil.

15w40 is a combination of mineral or synthetic oil + several friction additives. 15w40 contains detergents that absorb moisture from the fluid in the molecular form and do not create bubbles.

Multigrade oils are the best cleansing agent, and their capability of bearing high temperatures without changing the viscous property makes them best for all purposes.

Is SAE30 Thicker Than 15w40?

Sae30 is definitely a thicker engine oil than its counterpart 15w40 in cold temperature conditions. 15w40 remains thin in the cold weather and disperses well in the engine while Sae30 remains thick and doesn’t disperse well.

On the other hand, Sae30 perform well in high temperature and is limited to use in some old 2-stroke and 4-stroke diesel engines, whereas 15w40 can be used in hardworking cars, trucks, and SUVs.


Choose the perfect engine oil for your expensive vehicles wisely because you are going to use your vehicle for a long period of time.

Without the proper engine, oil or a bad cheap oil will lead to a high maintenance cost and severe wear and tear to your vehicle engine parts.

Sae30 is best for only high-temperature conditions and is only suitable to use in some 2-stroke, 2-stroke engines in oil devices and vehicles.

Whereas 15w40 is useful for varying temperature conditions and can be used for heavy vehicles such as trucks, buses, SUVs, and loading and unloading vehicles.

About The Author

Harry walter

Harry Walter is here, I'm a passionate writer of home guides, backyard, and garage problems, and have been doing this for a couple of years. I love to share simple solutions for your home and backyard problems.

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