Manufacturer recommendations

The service interval (how often the oil and filters are changed) is in the car's service book. What does this information actually tell us? In reality it's only the manufacturer's recommendation on how often to change the oil, calculated for certain operating conditions that the automaker considers average for this model of car (factoring in air pollution, fuel and engine oil quality, the car's class, regional operating conditions and much more). A sort of average temperature across the ward, so to speak.

With that said, the service interval is usually worked out in both kilometres and months (for example, as a requirement to change the oil at least once a year or every 20,000 kilometres of driving). All the other factors are accounted for by default, as described above.

For instance, if we're talking about a sporty convertible, the manufacturer is hardly going to plan around that car sitting in city traffic jams every day. And if it's a golf-class car, it's clear the average owner isn't cruising the highway every day at 180-220 km/h, even if the engine's power allows it.

Regional specifics make things a bit more complicated. Some car models are designed from the outset for particular markets, while for others manufacturers have more recently started setting differentiated service intervals depending on the country where the car was sold.