This has become even more complex in recent years, as modern engines are becoming smaller and more efficient, resulting in manufacturers setting strict specifications for the oils they use. For this reason, fully synthetic car oils have now been created, which are designed to withstand high pressures and meet the needs of low fuel consumption.

The type of car you drive, for example, if you own a sports or a European car, then it is very likely that the manufacturer will recommend using fully synthetic engine oil. On the other hand, if you own an older car, the manufacturer will recommend mineral oils.

Additionally, it is particularly important to know the factory specifications recommended by your vehicle's manufacturer, such as the type and viscosity of the oil.

You can easily find these important specifications in your car's manual (vehicle owner's manual).

What is viscosity in oils and what is its significance?

Viscosity in oils is a unit of density measurement that measures the “ease of flow” of a liquid. To better understand what viscosity is exactly, let's look at an example. For instance, water is a fairly thin liquid that flows easily, and for this reason, we can say it has a low viscosity. 

In the opposite case, if the liquid is, for example, honey, then we are talking about a thick liquid that flows much more slowly. Therefore, we can easily describe honey as a liquid with high viscosity when it is at a slightly high temperature.

As you understand, car oils behave in exactly the same way. You have surely noticed that when you go to the workshop for an oil change, the mechanic first runs the engine for 1-2 minutes before removing the used engine oils so that they can be replaced.

But what do the numbers on oil packages like 5W-40 mean?

The density numbers, as they are correctly called, indicate how thick a lubricant is, as we mentioned above. It is represented by 2 numbers, where the first with the letter “W” (Winter) refers to how the oil flows when it is cold, and the second to how the oil flows when it is hot under engine operating conditions.

Which type of oil should you choose?

You will notice that there are many car oils on the market and you will surely wonder which one is the right one for your vehicle. Let’s start with the three main types of oil, such as mineral oil, semi-synthetic, and fully synthetic.

Mineral oils are oils that have not undergone much processing, which means that these oils cost less compared to the others. Of course, protection, performance, and fuel economy are significantly lower.

The second type of oil is semi-synthetic oils, which are a blend of mineral oils and synthetic oils so as to offer additional performance, but at a lower cost compared to synthetic oils.

Finally, fully synthetic oils are comparatively the most expensive oils, as they undergo the most processing, but they offer better engine protection as well as greater fuel economy.

Specifications - International standards

ACEA: Standard from European car manufacturers.

• A/B: For gasoline engines and light diesel engines. (e.g. A3/B4)
• C: For engines with particulate filters (DPF). (e.g. C3)
• E: For heavy-duty vehicles (trucks).

API: American standard used worldwide.

• S: For gasoline engines (e.g. SN, SM)
• C: For diesel engines (e.g. CK-4, CJ-4)

ILSAC: Standard from American and Japanese manufacturers.

• It is mainly for gasoline engines and concerns fuel economy and emissions. Examples: GF-5, GF-6