SAE 40 vs 0W-40 Motor Oil – Which One Should I Buy?

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Buying the right kind of oil for your particular vehicle is very important. What kind of motor oil you use can affect the health of your vehicle’s metal parts.

Motor oil viscosity is one such element that can make or break the performance of your car.

Using an oil which has the right viscosity will ensure that you get more horsepower out of your motor, it will make fuel use more efficient, and slow down the wear of your vehicle’s parts.

The article below will be discussing SAE 40 vs. 0W40 motor oils and comparing their features so that you can figure out if any of them will work for your automobile.

SAE 40 Motor Oil

SAE 40 motor oils are said to flow best when the temperature ranges between 10℃ to 40℃ (or 50℉ to 104℉).

This is definitely an older monograde type oil whose use is becoming less and less nowadays.

However, there are still many applications for which SAE 40 motor oils are suitable and necessary.

Particularly, older and more classic engines require SAE 40 oils, as it is a mineral-based oil which prevents wear, sludge, and corrosion.

SAE 40 motor oils are great for use in turbocharged diesel engines and engines which are naturally aspirated, as they operate conditions both on highways and off them.

This oil can also be used in 4-stroke engines which have worn down, and when the manufacturer of an engine specifies the use of SAE 40 motor oil with that engine.

The SAE 40 grade motor oil ensures maximum protection of the engine by minimizing the number of deposits from the combustion and engine. It also lowers the consumption of oil in older engines.

Recommended SAE 40 Motor Oil to Buy

Now that we know the basics of the SAE 40 motor oil let us look into some specific brands which produce this excellent lubricant.

Valvoline VR1 Racing SAE 40 Motor Oil

Valvoline VR1 Racing SAE 40 Motor Oil

This is Valvoline’s (which is one of the most widely used brands of lubricants in the racing world) take on the classic SAE 40 motor oil.

It has a high phosphorus and zinc content, which ensures protection against wear for the engine.

Although it is said that SAE 40 oils are almost outdated and can only be used in older engines, this particular one is meant for high performing engines.

This SAE 40 oil is also specially designed to maximize your engine’s horsepower and reduce friction.

Even when the engine is under extreme levels of stress, this oil employs its anti-foam technology to protect it from damage.

The oil is also compatible with both part-alcohol and fully alcohol fuels. Though it is specifically made for racing engines, it is also suited for use in passenger vehicles.


  • Designed specifically to maximize horsepower
  • High level of zinc, as well as phosphorus in the oil, protects from easy wear
  • Widely used by professional and amateur racers
  • Offers great protection to the motor in high-temperature surroundings


  • Not suitable for vehicles which have catalysts
  • Relatively more expensive than other alternatives, given its race-level performance

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Valvoline Daily Protection SAE 40 Conventional Motor Oil

Valvoline Daily Protection SAE 40 Conventional Motor Oil

Another SAE 40 contender from Valvoline, this one is meant more for the regular driver rather than for professional racers.

Given its SAE 40 grading, you can rest assured that it will protect your engine to a large extent from corrosion, wear, etc.

The high quality of additives in this oil will also help the oil to not break down in the engine.

It also has added detergents in it which protect against sludge and other deposits forming in the engine.

Packaging may seem a minor detail to some, but this product’s easy pour spout and the anti-glug feature is definitely a bonus.

Even though this is an SAE 40-grade motor oil, it still flows decently well in colder temperatures.

However, you may find that it is not of the same quality as more premium conventional motor oils.


  • A great SAE 40 option for the everyday driver
  • Flows well in colder temperatures and higher temperatures alike
  • Keeps the engine running like it is new and protects from wear
  • Additives in the oil resist breakdown within the engine


  • May not be as high quality as premium conventional motor oils

Royal Purple ROY01040 SAE40 Synthetic Oil

Royal Purple ROY01040 SAE40 Synthetic Oil

Unlike the previous SAE 40 option, this one from Royal Purple is a synthetic motor oil rather than a conventional one.

But just like any other SAE 40 grade motor oil, this one also provides the engine with a great level of protection from wear, tear, and corrosion. It also helps maximize your engine’s fuel efficiency.

The oil also works well with engines containing catalytic converters and is compatible with fuels that contain ethanol.

Given that it is a fully synthetic oil (and not a synthetic blend), it is free from traces of crude oil, which are found in conventional motor oils. It also works seamlessly with other synthetic oils or mineral oils.

This oil can be used to fuel your car or lawnmower, or as a lubricant when working with metal parts such as struts and shocks, so it is quite multi-purpose.


  • Very affordable, especially if bought in a bulk carton
  • Produces much fewer deposits and sludge than conventional motor oils
  • Superior protection against corrosion and other forms of depletion
  • Highly compatible with ethanol-based fuels


  • The opening may not be the most convenient when pouring

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0W40 Motor Oil

Why 0W40 Oil

The 0W-40 oil is a more modern grade of oil that operates well across a very wide range of temperatures.

In fact, a typical 0W-40 oil can flow from temperatures of -40℃ to +40℃ (or -40℉ to 104℉).

If you look closely, you can determine that the 0 stands for the fact that this oil can flow as if it has 0 Weight in colder temperatures, that the W stands for ‘winter, and of course, the 40 stands for its temperature limit in degrees celsius.

This oil’s great performance in lower temperatures is what makes it a real multi-tasker and one of the most popular grades of oil in current times.

Simply put, in colder months, the 0W-40 motor oil can flow as if it is weightless but will also provide great protection to the engine against wear and corrosion.

0W-40 Motor Oils We Recommend

Let us now look into some specific brands of the 0W-40 motor oil which you can look into.

Mobil 1 120760 0W-40 Motor Oil:

Mobil 1 120760 0W-40 Motor Oil:

From probably the most well-known brand for motor oils (especially on the race track), this 0W-40 grade oil is fully synthetic and often exceeds industry and OEM standards for motor oils.

This is definitely one for more higher-end vehicles, but if the grade suits your four-wheeler, then you should give it a go.

The oil not only protects from engine wear but also cleans up any sludge or dirt that has collected in the engine previously.

Its exceptional frictional capabilities ensure that fuel efficiency is maximized.

This means that you need to change oil less often and get really good mileage.

And because it is a 0W-40 grade oil, it works and flows fine across a range of very low to high temperatures.


  • Protects the engine from build-up of deposits and also cleans it of existing sludge
  • Fuel efficiency is maximized thanks to its improved friction features
  • Great for use in extremely low or high-temperature climates
  • Eliminates engine depletion and reduces existing corrosion


  • The oil may leak after the seal has been broken, so you need to make sure to store it upright and never on its side

Castrol 06518 EDGE 0W-40 A3/B4 Synthetic Motor Oil

Castrol 06518 EDGE 0W-40 A3/B4 Synthetic Motor Oil

This is a fully synthetic 0W-40 motor oil from another reputed brand, Castrol, and belongs to its EDGE line of lubricants.

Needless to say, it performs impeccably in cold and hot conditions alike, flowing well regardless of the temperature.

You can also get a higher than average mileage out of this since it reduces friction and maximizes your engine’s performance and fuel efficiency.

It is also able to provide the engine with superior protection, given its blend of conventional and synthetic oils.

This oil also prevents sludge and other harmful deposits from building up and cleans the engine of existing dirt. It also protects the engine from depletion and oxidization.


  • Maximizes your engine’s performance by reducing friction
  • Protects against general wear, oxidization, and deposits in the engine
  • Flows smoothly in both extremely cold and extremely hot conditions
  • Maintains its viscosity to a higher degree than most other fully synthetic motor oils


  • As with most bottles of motor oil, this one is also not very pouring friendly and may require the use of a funnel

Liqui Moly 2050 Synthoil Energy 0W-40 Motor Oil

Liqui Moly 2050 Synthoil Energy 0W-40 Motor Oil

This is a low viscosity and fully synthetic 0W-40 grade motor oil from Liqui Moly.

Aside from flowing freely across a range of cold and high temperatures, it also ensures a quick start-up for the engine in cold weather.

Not only does it keep deposits from building up within the engine and affecting its performance, but it also cleans the engine and has great dirt suspending features.

This oil also keeps oil consumption at a minimum, increasing your engine’s fuel efficiency and also giving you more mileage for every quart.

It can be used across a range of vehicles (including ATVs) and is suitable for many of the high-end cars, such as BMWs and Audi’s.


  • Retains its viscosity over a very wide range of temperatures
  • Reduces oil consumption, hence increasing fuel efficiency
  • Starts pretty quickly in colder weather
  • Prevents build-up of dirt and also cleans the engine of existing harmful deposits


  • You may need to change the oil a bit more frequently than usual

SAE 40 Motor Oils or 0W-40 Motor Oils?

There are several differences between these two grades of motor oil. But let us look at some of the more prominent ones which can impact your decision to buy one or the other.


SAE 40 motor oils have been around for a long time. This explains their simplistic grading and why they are mostly used in older engines.

The oil has a singular high-temperature viscosity but flows thick enough to protect the engine greatly from regular wear.

SAE 0W-40 is not as old as SAE 40 and is a synthetic blend of oil, which is why its viscosity ranges from very low temperatures to higher temperatures.

In a way, it is the best of both worlds because not only does it flow like a zero weight oil, it also offers the protection of something much more viscous than it is.


As we know, the 0W-40 oil flows well across a much wider range of temperatures than the SAE 40 oil.

The 0W-40 is suited for very cold environments but can also flow nicely in hotter climates.

However, the SAE 40 oil is not as multi-functional and can only flow well from 50℉ up to 104℉.

But which of these you use will ultimately depend on what the manufacturer of your vehicle’s engine recommends.


This is one area where the two grades of oil really do not differ that much. Depending on which brand you buy them from and in what quantities, either SAE 40 or 0W-40 can be more or less expensive.

And if your vehicle’s engine is only suited to one grade of oil or the other, then the price does not really matter since you will have to buy that specific grade of oil anyway.


Motor oil viscosity may seem like a minor factor, but is a very important one for the health of your car and its components.

And after this SAE 40 vs. 0w40 guide, choosing a motor oil, which has a viscosity that suits your vehicle and its surrounding weather, should be a breeze for you.