Replacing the air filter
The engine air filter ensures that the air entering the engine is cleaned from sand, dust and other impurities. Usually, car manufacturers recommend changing the air filter every or every second oil change. If you drive a lot in dusty environment, for example on gravel roads, it is worth checking the condition of the air filter more often, and if it is visually dirty, replace it. Air filter price is on average 10 - 20 EUR and it is usually so easy to replace it that you can even do it yourself without special equipment. Air filter change price is usually not more than 10 - 20 EUR, it is often done together with other maintenance work.

A dirty air filter reduces the amount of air entering the engine, which can result in increased fuel consumption, reduced performance, and unstable engine operation. If the air filter is damaged, both dirt from the outside environment and particles from the filter itself can enter the fuel intake system and the engine, causing serious and costly damage and contributing to increased engine wear and reduced engine life.
In summary, a car air filter is so cheap and easy to replace that it's better to change it a little more often than to miss a change!