10w30 vs 15w40

If you buy something through a link in our posts, we may get a small share of the sale.

Is it time for an engine oil replacement in your vehicle? And are you in some confusion between the 10w30 and 15w40 oils, which are both compatible for use?

If yes, then you are probably not aware of how viscosity acts upon your vehicle’s engine. Basically, viscosity is what determines the flow of engine oil within the internal components of an engine. Therefore, the lower the number for viscosity, the better will be the flow.

10w30 vs 15w40

If you have a vehicle or industrial equipment used for high-intensity performance, you will need an ideal oil. And, you need to look for the one that is of low viscosity before you can pick anything random.

Moreover, if your vehicle is compatible with both 10w30 and 15w40, knowing the similarities and differences will help you decide. Therefore, check this 10w30 vs 15w40 article to know more about these two oils.

10w30 Specifications

10w30 is a popular multi-grade engine oil suitable for heavy-load engines, whether an automobile or industrial equipment. It has high potential in enduring the engine’s high temperature, for a long time, without adversely affecting the engine’s efficiency.

However, at the same time, it also gives an excellent pump to the engine at low temperatures. For low temperatures, this engine oil comes with a viscosity rating of 10, whereas for high operating temperatures, the viscosity rating is at 30.

A close up shot of a machine with cylinders and circular chain

The American Petroleum Institute has set up some ideal conditions and standards for the oil that you must prefer in your car.

First, the oils should have the API SN rating to be preferable for cars or other engines. This rating specifies that the oil has the potential to protect the piston from deposits generated due to combustion.

Sludge management is also an effective perk of 10w30 motor oil and is also compliant with the machine’s sealing and aftercare aspects.

As per the European Automobile Manufacturers Association, the motor oil that comes with ACEA A3/B3 or ACEA A3/B4 ranking is compatible to be used in vehicles. The ACEA A3/B3 and A3/B4 ranked engine oils are suitable for light-duty vans and passenger cars with diesel or gasoline engines.

10w30 has quite a lot of advantages over other oil types such as SAE30, 5w30, and 5w40. It wraps up a continuous coating over the engine components, thereby reducing the friction between them.

Therefore, it has the potential to minimize the wear and tear on the engine and keep it cool during the start or stop process. Moreover, it also prevents the components of the engine from experiencing corrosion. Hence, it will contribute towards increasing the life of the engine with seamless clutch & gear operation.

15w40 Specifications

15w40 is yet another high-performance motor oil that is of synthetic-plus grade. It is a heavy-duty oil, which is highly preferable, primarily for diesel engines. Diesel engines often experience more wear and tear in comparison to other fuel-compatible engines.

Therefore, they need optimal engine oil to reduce wear and tear and other adversities. In addition, 15w40 oil has the potential to protect such engines from soot contamination, aeration, deposit formation, and oxidation.

Moreover, 15w40 comes with triple-protection-plus technology, the benefits of which are embedded within the diesel 15w40 engine oil. Also, this oil consists of additives and synthetic-based oils.

This, in turn, offers more resistance to oil breakdown and deposits, thereby enhancing oil flow at low temperatures. The usual manufacturing blend of this oil determines the viscosity of 15 at low temperatures and 40 at high temperatures. It is specified over the name of this oil type.

An engine block to deposit the oil

The synthetic blend of this motor oil intends to protect the machinery with proficiency and extends the engine life. However, it also retains the regulation of viscosity at high operating temperatures.

15w40 synthetic plus blend is ideal for heavy-duty engines, such as highway fleets, agriculture equipment, manufacturing equipment, diesel trucks, and other high-power demanding vehicles.

Such vehicles or equipment are often in demand for high resistance to tension, friction, and heat. Therefore, 15w40 is an ideal pick for the same.

The formulation of the 15w40 motor oil offers ideal performance against oxidation. And degradation resistance at high operating temperatures is also a considerable perk of this motor oil type.

Moreover, its tripe protection potential aims to increase the engine life by retaining its performance over time.

Similarities of 10w30 and 15w40

  • Both of these oils are offering ideal protection against oxidation and sludge build-up.
  • Both these oils do meet the required standards to be used in vehicles for shielding the pistons.
  • Even though with different viscosities, both of these oils are preferable to vehicles for all climates.
  • Both 10w30 and 15w40 oils prevent oil breakdown conditions in critical scenarios.

Differences of 10w30 and 15w40

  • 10w30 is ideal for engines that have completed over 75000 miles. The 15w40 oil is compatible with the engines that meet the API CJ-4 requirements or exceeds them.
  • 15w40 motor oil supports a longer drain interval than that of 10w30.
  • The low temperature viscosity rating for 10w30 is ’10’, whereas for 15w40, it is ’15’.
  • The high-temperature viscosity rating for 15w40 is ’40’ whereas for 10w30, it is ’30’.

Major Distinguishing Factor

The major distinguishing factor between 10w30 and 15w40 is in their performance aspects. 10w30 consists of a high film-strength blend solution. And, 15w40 consists of triple plus protection.

On the one hand, the 10w30 consists of zinc additives with anti-wear properties, whereas 15w40 supports 37% more wear resistance than its maximum manufacturing criteria.

An oily engine block removed from the car

When to Use 10w30?

10w30 is an ideal consideration for petrol and gasoline engines. Also, it is suitable for passenger vehicles and light vans for any region with seasonal changes. Furthermore, 10w30 is ideal for both low and high-temperature scenarios.

When to Use 15w40?

15w40 is ideal for heavy-duty diesel engines such as trucks, industrial equipment, highway fleets, etc. These vehicles generate more heat within the engine and require optimal oil to resist it from causing damage. It is also preferable for use in vehicles or equipment operating in all seasons.

Final Verdict

Both of these engine oils are best in their ways. So, you need to check with the manufacturer’s details before opting for any one of them. If your vehicle or equipment is compatible with these oils, then look at the differences and similarities to decide the one that suits your needs the best.