Difference Between 0W-40 and 5W-40 Engine Oil

For the internal combustion engine of machines or vehicles to function correctly, it needs engine oil. There is adequate clearance between the hundreds of moving parts in a vehicle’s engine. 

These adequate clearances require sufficient oil to act as a protective layer and lubricate the moving parts. Without this oil, your engine can overheat, grind, or even stop totally.

Even the best of the best engines which have been carefully designed will not function well without oil circulating around it and will eventually grind to a halt. The oil is vital to keep all parts moving effortlessly.

Although all engine oil performs the same duty of helping the moving parts run smoothly, they are created differently. That is to say that engine oil varies in quality, quantity, model, and types.

This article briefly looks at the different oil forms, although the primary focus is on 5W40 and 0W40 to ascertain which is better. 

Heat Resistance 

When the engine oil does not lubricate the engine, it can cause the engine to overheat. Engines that are high in performance usually emit more heat compared to the low-performing engines. Thus high-performance engines need an oil that can withstand the highest temperature.

Certain oils become thin when they face high temperatures, and their protective ability gets reduced. This explains why your car sometimes stops working abruptly by the roadside and gets filled with a cloud of smoke.

So you must choose oil that can stand high temperatures.

Wear Protection

Naturally, vehicle owners expect engine oil to make a thin barrier between all the engine components that move. When these moving components brace against each other, they could get ground down, and then the adequate clearances between them could get too large. 

The result of this is inefficiency, along with other serious engine issues. Therefore, it is recommended that you choose engine oil products that are tested and approved to keep that lubrication barrier between the moving components.

Mineral Deposit Protection

A mixture of air or fuel is needed for all internal combustion to be burned. A perfectly timed and controlled explosion pushes down a piston in its cylinder and gives rooms for turn-over of the. 

This combustion reaction produces some byproducts from the burning of air or fuel mixture. Engine oil that is of good quality has chemical compounds that are known as detergents.

Detergents eliminate the engine oil impurities by carrying them to the engine’s oil filter, where it is removed. If not removed, engine oil impurities cause reduced efficiency or even more significant damage to the engines.

Protection Against Oxidation

The importance of combustion engines to your car’s engine cannot be downplayed. They are crucial to the engine’s good working condition, although they also need oxygen to burn.

This oxygen has water vapor in it, which is impossible to split away from the flammable gas. This water vapor is not ideal for your engine; they make your engine’s metal internal parts to rust (otherwise called oxidation).

The good news is that if you buy engine oil of high quality, it puts everything in the right protection layer and prevents the water from making contact with the metal parts. This acts as a robust defense mechanism to your engine and keeps it from the process of oxidation.

Features to Consider When Choosing Motor Engine Oil

Tier Which the Oil Falls

Motor oil falls into three basic tiers which are:

  1. Conventional oil: ancient oil that has been in existence for long. It is referred to as old-fashioned oil, but it is cheap compared to others. However, this oil does stay effective for too long and needs to be replaced at frequent intervals.
  2. Full Synthetic: by various standards, this is the ideal tier of oil. It gives maximum protection to the engine and allows them to perform at a high level. Although it is more expensive than others, it stays effective for long and does not need to be changed often.
  3. Synthetic Blend Oil: which merges the protective features of full synthetic oil along with the cheapness and simplicity of conventional oil


The thickness of motor engine oil changes based on temperature; thus, you must choose an oil suitable for your area’s climate.

Oils that are too thick are not suited for areas with cold climate, and they can even make it difficult to start a cold engine. Similarly, a thin oil does not offer adequate protection to the engine against performance-robbing dirt, heat, and friction.

SAE Rating System

This is a standardized system put in place by the Society of Automotive Engineers (SAE) to denote motor oil viscosity at different temperatures and enables you to know if you are using the right type of motor oil. 

SAE classified motor oils using numeric codes, which are divided into two parts.

  1. The first code number denotes the viscosity of the oil in cold temperatures. It states that the lower the oil’s viscosity, the easier the oil will flow around your engine when you start the engine on cold mornings.
  2. The second code number depicts the engine’s viscosity at an average running temperature (212F). 

Too thick oils reduce efficiency while too thin oils reduce protection.

5W40 vs. 0W40: Which Oil is Better?

With the knowledge we have gained on oil rating, we can now juxtapose which of these oils is better. 

In terms of the second code number, both oils have similar viscosity when heated at regular engine running temperatures.

Their significant difference is in their first code number. 0W40 circulates through and start your engine quicker than 5W40. So if you live in an area with a cold climate, 0W40 is better for your car engine than 5W40.

However, 0W40 can be too thin to start your engine and give it adequate protection in areas with hotter temperatures.

Conclusion – Can I Use 0W40 Instead of 5W40

We are hopeful that this article has given you insight on oil rating and will guide your choice of oil for your car engine. 

To get more information, you can consult your car owner manual and go with the oil recommended by the manufacturer.

Motor engine oil is essential to your car’s engine, so it is pertinent that you use the right one.

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