How to choose the viscosity for a car?

Last updated of 4 April 2025 by Maxime de Prinel

Choosing the right engine oil is not only a question of brand or price, but above all a matter of viscosity. A scarcely adapted oil can cause premature engine wear, excessive fuel consumption and even faulting. So how do you know which oil to choose for your car? Follow the leader !

What is the viscosity of a engine oil?

Viscosity is the ability of a liquid to flow. An oil is more fluid, more easily it circulates in the engine. On the contrary, if it is too often, it will find it difficult to correctly lubricate the parts.

Engine oils are classified according to a standard SAE (Society of Automotive Engineers)with indications such as 5W-30 OR 10W-40.

🔹 The first figure followed by «W» (winter) It represents the fluidity of the oil in the cold. The lower this figure, the more the oil remains fluid in winter, which facilitates the beginning.

🔹 The second figure Indicates the viscosity of the hot oil. The higher it, the more the oil remains the more often when the engine works at high temperature, thus offering better protection.

💡 Example : An oil 5W-30 it will be colder fluid than an oil 10W-30But they will have a similar viscosity once the engine is hot.

1. Follow the manufacturer’s recommendations

The simplest: look in Vehicle manual. Manufacturers specify the ideal oil for their engine taking into account the design and conditions of use.

2. Suitable for climatic conditions

🌡 Cold → favor an oil 0W TU 5W To facilitate Start -Up.
🔥 Hot climate → opt for an oil with a high hot index, like 10W-40 or 15W-40.

3. Take your driving style into consideration

🚗 Short routes in the city → a fluid oil (5W-30) it is preferable to reduce usury due to frequent games.
🏎 Long distances, highway, heavy loads → A more viscous oil (10W-40, 15W-50) will offer better protection.

The different types of engine oils: which one to choose?

You have three main categories of engine oil on the market:

🛢 Mineral oil → Suitable for old engines, but requires more frequent changes.
⚙ Semi-synthetic oil → a good compromise between protection and prices, suitable for standard vehicles.
🔬 Synthetic oil → The most efficient: better lubrication, fuel savings, duration of prolonged life. Ideal for modern engines.

Which engine oil to choose? Our advice

If you don’t know which product to contact you, here are some popular references:

✔ 5W-30 → Ideal for recent engines and cold/moderate climates. Example : Total quartz ino ECS 5W-30.
✔ 10W-40 → versatile, for vehicles more kilometers on the clock. Example : Castrol GTX Ultraclean 10W-40.
✔ 15W-40 → Perfect for old vehicles and hot climates. Example : ELF 15W-40 evolution.

In summary: engine oil, a choice not to be overlooked

Take the right oil is to guarantee a Best longevity to your engine And avoid many mechanical concerns. Remember to regularly check the oil level and respect the exhaust intervals for a shape -shaped engine! 🚗💨

👉 Small bonus advice: If he results between two clues of viscosity, Ask for a mechanical advice or a specialist in lubricants. A bad choice could be expensive in repairs!

With this article, you now have all the keys to choose the engine oil. So, ready to offer your car the best possible protection? 😃