Motor oil – Why and how we should take care of it


Motor oil, when properly selected, regularly changed and maintained at the right level, allows us for a very long use of even the most exploited propulsion unit and related equipment.

Types of motor oil

There are three types of motor oil available on the market – synthetic, semi-synthetic and mineral. Synthetic oil is characterised by its best properties and is used in pretty much all new cars manufactured within the last few years. Semi-synthetic oil, on the other hand, was the standard as recently as about 15 years ago, but it's slowly falling into obscurity these days. Sometimes drivers go for it when the engine starts using more synthetic oil than it should. However, we should only experiment like that when assisted by a good mechanic.

What type of motor oil should we use?

The answer to the question of the exact type of motor oil we should use can be found in our car's user manual. It should specify not only the type of oil but usually the recommended brand too. It is better to stick to those guidelines, and if we want to save some money on buying oil from a good brand, we might order it online. It is pretty common for the same oil that costs nearly 50 EUR for 4 litres on a supermarket shelf to be available online for 30 EUR which already includes the delivery.

Why should we even buy the motor oil on our own if we usually get mechanics to change it anyway? Unfortunately there are mentions of mechanics putting low-quality oil in the engine when changing it, while „sucking” their clients dry like for a top-quality one. Not to mention a mechanic who has to buy our oil right here and right now will focus on buying it fast, not cheap. After all, it's not them who's going to pay the bill in the end, it's the client.

The least trusting repair shop clients even try to be present when the oil is changed to make sure the right one is put in. Most mechanics, though, use a certain trick to prevent them from this kind of supervision. They pick up the client's car at a particular hour but don't say when they'll get to it, and we know that no driver would like to sit at the repair shop all day.

But let's get back to what kind of motor oil we should use. If our car's user manual got lost somewhere, we can print out one available on the Internet. We should also be able to find the same info on the right type of oil for our car on the sticker under the hood. We may also refer to our service booklet, where the entry for every oil change should also mention the type of oil used.

How often should we change the motor oil?

Motor oil should be changed every 10-15 thousand km, but no less than once a year. (take a look at this engine without oil change) Let us not get fooled by the aggressive marketing of oil manufacturers, who often say that we can do it less often. They're not the ones who will have to pay for sooner engine repairs or a malfunction of the turbocharger, we are. Turbochargers often tend to be more sensitive to the quality of oil than engines themselves. Even if it won't hurt the engine to change oil every 20-25 thousand km, it might be too much for the turbochanger to run so long on the same oil. It is worth noting that even the official manufacturer's data tend to be flawed here. Everyone back in the day heard about Renault Megane III 1.5 dCI with Garrett turbocharger. Renault professionals claimed that it's enough to change oil every 30 thousand km, meanwhile the turbocharger's manufacturer suggested to do it every… 15 thousand km, which is twice as often.

We also shouldn't trust the tales from older car users about how they used the same oil for 60 thousand km and „everything was fine”. Let us remember that people who tend to say such things often have cars older than 20 years, which technologically speaking is a different era. By the end of 1990s it wasn't common to get 185 horsepower out of a 1,4 liter engine, or 235 horsepower out of a 1,8 liter one, as is the case these days with Audi A1 or Alfa Romeo Gulietta. Today this kind of results is nothing unusual. Engines are exploited to their extremes, which is why we have to provide them with the best lubrication available.

How often should we check the oil level?

Regular oil change is not enough, though. We should also check if the motor oil isn't leaking somewhere and if the oil level stays at the 3/4 of the distance between the min and max marks on the oil measuring dipstick. Why this exact oil level? Not enough oil might wear off the engine, whereas too much of it increases pressure in the engine and might get it broken or unsealed.

We should check the oil level every 2 or 3 weeks, unless we really drive our car around a lot. In such case we obviously have to do it more often. Oil level check should be performed when the engine is cool and the ground is flat. It is also a good idea to check the oil level manually from time to time, even if our car does have a dedicated sensor. Electronics aren't always reliable, after all.