How do manufacturers calculate the interval?

Time doesn't stand still, and it's pretty obvious that the era of "immortal" cars is long behind us. Car manufacturers haven't found it profitable for a long time now to build cars that don't break down for decades, because they need to somehow keep their sprawling service networks running, and to keep pushing consumers towards buying new cars.

So, oddly enough, when a car manufacturer works out the recommended oil change interval, longevity of the engine over the long term isn't really its concern at all. What matters to the manufacturer is how the engine performs during the factory warranty period, and what happens to the engine after that is largely beside the point. What's more, it's actually in the manufacturer's interest for the car's owner to visit an authorised service centre more often once the warranty period ends, or to start thinking about buying a new car as soon as possible.

So for a car manufacturer, the service interval is essentially a marketing concept, and the main task when calculating it is to keep warranty service costs to a minimum while making the car as attractive as possible to a potential buyer. Long oil change intervals in particular have recently become an extra selling point used to attract buyers.

How justified that is in our conditions is for you to judge – how often to change the oil in your engine is your call to make. The main point of this article is that the service interval recommended by a car manufacturer is far from always the ideal maintenance plan for your car.