Which engine oil do I need?

The engine oil dashboard light comes on, but arriving at the petrol station you have no idea what the differences are between 5w30, 10w40 and 5w40 engine oil. Of course, it is always better to add with whatever oil you have, than to continue driving with no oil or too little engine oil. Fortunately, the owner's manual (if you still have one) often gives the answer. 

In case you no longer have it or it is safely stored at home, Autobook offers a solution. On this page, we discuss the differences between 5W-30, 5W-40 and 10W-40, among others. These are the most commonly used engine oils and on one of these three, almost all cars can safely continue on their way, without the risk of engine damage due to insufficient oil. Also give a quick step-by-step guide on how to change the oil yourself. 

Of course, as you have come to expect from Autobaak, we have made an overview of the motor oil needed per make and model. This overview of engine oils can be found at the bottom of this page. You first click on the brand and then go to the model overview.  

What does the "W" stand for in motor oil? 

The the letter "W" in e.g. 5W30 stands for viscosity. The value before and after the W indicates how the oil behaves at low and high temperatures. If the letter before the W is low, the oil is more fluid at low temperatures and the car will reach operating temperature faster and start more easily. The number after the W says something about the thickness and performance of the oil at a temperature of 100 degrees. So the higher the number after the W the better the lubricity is at high temperatures, only this oil is also thicker at operating temperature which in turn can mean higher fuel consumption, and of course with today's fuel prices we want to avoid that at all costs. 

You might think "but my car never gets that hot" and that is true. This is particularly true of diesel engines. These never reach an operating temperature of 100 degrees. On the other hand, there are more and more small engines with a lot of power due to the use of a turbo. With these engines, it is not inconceivable that they do sometimes operate at 100 degrees and thus require a different type of engine oil than the aforementioned diesel engine. We will now elaborate on the differences between 5W30, 5W40 and 10W40.  

5W30 engine oil

So in practice, 5W30 should provide better starting because this oil is thinner at low temperatures. At higher temperatures, 5w30 engine oil theoretically gives slightly less stable lubricating film. Still, most cars can function well on 5W30 and the advantage is that the car reaches operating temperature earlier and provides less fuel consumption.

So 5W30 motor oil, if permitted by the manufacturer, is suitable for people who drive short distances (a lot in the city, for example). In addition, you see that this oil is widely used in diesel engines. This is done because the operating temperature is usually lower in a diesel engine. And finally, we should not forget that the change of the maximum speed, from 130 km/h to 100 km/h also affects the operating temperature. 

10W-40 engine oil

So when you use 10W40 motor oil, a car may not start as easily, although you may not notice this yourself, the engine does. In addition, it takes longer for the oil in your engine to reach operating temperature. And this is an important difference with 5W30. If your car's temperature gauge reads 90 degrees, this does not necessarily mean that the oil is also at temperature.

So in practice, you may end up revving more without the 10w40 engine oil being up to temperature. At higher temperatures, this oil does function better. So this can apply to engines that have been downsized (1.0 turbo engines) and in addition, the outside temperature and driving style affect operating temperature.  

5W-40 engine oil

So is 5W40 motor oil the best compromise between 5W30 and 10W40? You might be quick to think so. The engine starts easily because of the 5 before the W and lubricates better at higher temperatures because of the 40 after the W. Whether this motor oil works best for your car also depends on your driving style. For example, if you mainly drive motorway kilometres, then (depending on the engine) the car may struggle to stay at operating temperature and thus not benefit at all from thicker oil. 

Engine oil vintage cars

If you are looking for motor oil for your oldtimer, we advise you to use the motor oil from Kroon, which has developed a line especially for oldtimers. The 20W-50 and 15W-40 motor oils are particularly well suited.

Changing engine oil

If you own a car, it is important to know how to change the engine oil. Engine oil keeps the engine running smoothly and efficiently. Over time, motor oil breaks down and becomes less effective. Therefore, it is important to change the engine oil every few months.

Most car manufacturers recommend changing engine oil every 15 to 20,000 km, but this may vary depending on the make and model. Consult the owner's manual for specific recommendations on engine oil changes. You may also need to change the oil more often if you do a lot of traffic jams, drive short distances or in extreme conditions (e.g. hot or cold weather).

Our recommendation

Fortunately, with the advent of multigrade engine oils (oil functions at different temperatures), you no longer need to change oil depending on the season. Most engine oils function well all year round. Still, when the manufacturer allows both 5W30, 10W40 and also 5W40, you can choose an oil that best suits your driving style.

So if you drive a lot of short stretches and want to make sure your car gets up to operating temperature quickly, choose a 5W30 or a 5W40. If you have a small engine that revs relatively frequently and you drive a lot of motorway miles in the summer months, then it may be smarter to go for a 10W40. And remember that warming up slowly (20min) helps the life of any engine. Want to be sure which engine oil is best for you? Then use the overview above.