Filter: "magic" word for cars. Because we are talking about eliminating the superfluous and harmful, in favor of substances that are instead good for the vehicle. In fact the filters (we are referring to them) protect all parts of the engine, do from shield against dirt, especially against metal residues and tiny particles. There are companies specialized in car filtering technology, but the first step is always up to you: you need to respect the maintenance coupons and the regular replacement of the filters over time (indicated in the user manual). And if you notice any strange problems (we tell you which ones below), run to the workshop.

1 # Petrol and diesel filter. Generally, petrol filters are able to filter out tiny impurities, even those of a thousandth of a millimeter. If you "feel" loss of engine power, a visit to the mechanic is urgent. As for the diesel filters, they protect the injection system and the engine from particles from enemies such as water and other residues: if they are dirty, there will be drops in engine power until it stops.

2 # Oil filter. Even the oil contains impurities, which absolutely must not reach the engine, thanks to the filter. On stop-and-go journeys, oil filters are put to the test, even more so in winter: cold starts cause "condensation" and an excess of fuel in the combustion mixture, to the detriment of lubrication quality. The alarm bells are a small oil spill, as well as reduced performance.

3 # Air filter. If the air is not properly filtered, the air-fuel mixture is poorly prepared: engine performance will drop (you will notice it) and the emission of harmful substances will be stronger (not easy to be sure). The most important "spy" is a strenuous starting of the car.

For the interior

A separate discussion for the cabin filters. They protect whoever is driving from pollen, dust and polluting particles; protect the air conditioning system. Roughly, they must be changed every 15,000 km or after a year, but who often drives in a traffic clogged metropolis (and submerged in smog) will be forced to replace them more frequently. Watch out for ultra low cost filters, which do their job badly. Ideally, a multi-layered cabin filter, with the central layer of electrostatically charged microfibres, which attracts small particles. Those we breathe and which risk penetrating deeply into the lungs.