Is it once a year, every 30,000 km, or maybe every 100,000 km? There’s a lot of different opinions on how often one should change engine oil. Let’s find the one that’s closest to the truth.
Why change engine oil in the first place?
Engine oil ensures that the engine and the turbocharger function properly. Its condition is all the more important because each year new engines appear on the market which are built in accordance with the idea of downsizing. Simply put, it means maximizing the power of the engine without increasing its capacity (or even despite reducing it). Thanks to this, modern engines have very low fuel consumption and generate less pollution while maintaining high power. Still, as usual, this comes at a certain price. Horsepower doesn’t just “come from” increased capacity; it’s (among others) the result of the work of additional equipment, such as the aforementioned turbochargers. Modern engines are maximally optimized; engineers try to construct them so as to take full advantage of their capabilities. This results in the engines being subjected to extreme stress. Excellent performance generated by high engine power and turbochargers requires perfect lubrication. This is why in today’s cars synthetic oils are usually used, while a dozen or so years ago, semi-synthetic oils were more popular.
Unfortunately, even synthetic oils lose their qualities with time. In diesel engines, kilometer by kilometre, oils become less and less able to disperse the accumulated soot. In LPG-powered units oils gradually lose their ability to resist the formation of acids. In every engine, due to high temperatures and extreme stress, the distribution of oil to less accessible places such as turbochargers or cylinder heads, gets slower and slower. If this situation drags on for a long time, it’ll cause faults in these components. To avoid it, change oil regularly.
How often should you change engine oil in new cars?
Tips on how often to change the oil can be found in the instruction manual of your car. However, don’t expect a vehicle manufacturer to suggest changing the oil less often than every 10-15 thousand km or every year. Even if they did, the instructions to change the oil every 25-30 thousand km should be treated with reserve, especially if you want to be able to use your car for a long time.
Besides, even if you have developed the habit of selling cars after reaching the mileage of 80-100 thousand km, it’s more likely that the potential buyers will trust you if they see a confirmation of frequent oil changes in the service book. The buyer will rightfully believe that the fact that the first owner cared for systematic oil change means trouble-free operation of the engine and turbocharger for tens of thousands km.
How often should you change engine oil in used cars?
Caring for the condition of engine oil in used cars is even more important than in brand new vehicles. There may be no repercussions for the engine or turbocharger if you neglect regular oil changes in a new car; in fact, it may turn out that the second owner will be more affected than yourself. Meanwhile used cars, in which these parts have already been affected by the passing of time, can be much more prone to the faults resulting from the use of oil which has already lost its properties.
So the answer to the question “how often should you change engine oil in used cars” is the same as in the case of new cars: not less often than every 15,000 km or every year. So why can you encounter different suggestions?
First of all, strong competition can push the marketers to praise the durability of their product so enthusiastically you shouldn’t trust them. That’s why we advise treating the assurances of producers of so-called long-life oils (which, according to the declarations, retain their qualities for 30.000 km) with reserve. Remember that it’s you, and not the oil producer, who’ll pay for expensive engine repair or turbocharger regeneration. What’s more, the durability of the oil is like fuel consumption: the catalogues try to convince you that the product will work wonders but the reality rarely confirms this.
Secondly, there’ll always be people who were just lucky, despite their reckless behaviour. Every one of us likely heard stories about a “friend of a friend” who travelled 50 or 100 thousand km without changing the oil and “nothing bad happened to them”. You should always ask yourself if you should really believe in such stories. Besides, the fact that nothing is broken at the moment doesn’t mean that no repairs are coming soon.
Remember that the cost of changing the oil is really low when compared to the other costs of car maintenance. In online stores, a 4-litre container of branded synthetic oil usually costs up to 150 PLN with shipping included! Of course, you will also need to buy an oil filter and pay the mechanic, unless you’re able to change the oil and the filter by yourself. It shouldn’t cost more than 300 PLN. Is such money worth risking engine repair or turbocharger replacement? These would cost you many times more!