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Difference between 5W30 and 5W40: It's a question many motorists ask when standing in front of the motor oil shelf. Both oils are very similar, but have just enough difference to affect performance, wear and fuel economy. In this blog, we'll clearly explain to you how these oils compare, and help you make the right choice for your vehicle.

What do 5W30 and 5W40 mean?

The number before the W represents the viscosity at cold temperatures (the "W" stands for winter). The lower this number, the thinner the oil is at cold start-up. The second number (30 or 40) refers to viscosity at operating temperature, or how thick or thin the oil is when the engine is fully warmed up. 5W30 is thinner at warm temperatures than 5W40.

What does that difference do in practice?

5W30 flows slightly easier through the engine at higher temperatures, providing slightly less internal friction and thus better fuel efficiency. 5W40 is thicker at operating temperatures and therefore often offers somewhat better protection in older engines or at higher loads. The difference is subtle, but noticeable at long-term loads or higher temperatures.

For which engines is 5W30 suitable?

5W30 is suitable for most modern gasoline and diesel engines, especially those fitted with particulate filters or meeting stricter emission standards. This oil ensures a good cold start and remains flexible in warm conditions, making it ideal for normal daily use. You can always find the correct specifications in your car's instruction booklet.

When do you choose 5W40?

5W40 is often recommended for older engines, engines with higher mileage or vehicles that operate under harsher conditions, such as in hot climates or with a caravan. Because this oil remains thicker at high temperatures, it offers just a little more protection against wear under load.

Does it really matter that much?

Yes, while both oils perform fine in many cases, the difference can affect how your engine runs, how much fuel you use and how much wear and tear occurs. The important thing is always: follow your vehicle's specifications. If your car is designed for 5W30, don't use 5W40 unless a specialist recommends it.

What does the manufacturer say?

Car manufacturers test engines with specific oil types. So this recommendation does not come out of the blue. They take into account internal tolerances, oil pressure, temperature and emission requirements. So always check the service booklet or use a reliable oil search tool like the one you find at solution-oil.com.

Where do I buy reliable oil?

At Solution Oil you will find only top quality premium motor oil. Our Premium Performance 5W30 is a popular choice for modern engines and meets the most stringent standards. Order easily through our webshop Or contact us for advice.

Giving insight is our mission

We think it's important that you know what you're pouring into your engine. Good oil prevents problems, saves on repair costs and extends the life of your vehicle. Find out more about our team and our mission at the about us page or find our background here in Weert.

Frequently asked questions (Q&A)

1. What is the difference between 5W30 and 5W40?
5W30 is thinner at high temperatures, providing less internal friction. 5W40 is thicker and provides better protection under heavier engine loads.

2. Can I use 5W40 instead of 5W30?
Only if permitted by the manufacturer. Always use the recommended viscosity to avoid damage.

3. Which oil is more economical in consumption?
In general, 5W30 is slightly more economical because it allows the engine to run more lightly at operating temperature.

4. Is 5W40 better for older cars?
Yes, especially when the engine has some more miles or starts to consume oil. The thicker structure protects better in case of wear.

5. Will it hurt if I use the wrong oil?
This can lead to additional wear, higher temperatures and, in some cases, even damage to your engine or exhaust aftertreatment.

6. What if my car allows both?
In that case, you can choose depending on your driving style: 5W30 for normal use, 5W40 for heavy loads or higher temperatures.

7. Are both oils suitable for diesel engines?
Yes, provided they meet the correct specifications (such as ACEA C3). Always check the manual or product information.

8. Where can I order the right oil?
Retrieved from solution-oil.com easily and quickly order oil that perfectly matches your vehicle.