In our atmosphere, there are lots of unhealthy floating particles and substances that can damage internal engine parts. Air filter prevents such particles from entering the engine prolonging engines life.
Air is suctioned inside the engine combustion chamber. In absence of air filter, particles can enter inside the engine and can stick with oil inside the cylinder wall and acts like emery causing premature wear of cylinder, piston and valves.
Normally air filter used in automobiles are of Paper type, Foam type and Oil bath type. Paper filters use special kind of pleated semi-permeable paper. Intake side of paper filter is courser while the engine side is fine thus dust are trapped inside the filter paper giving cleaner air to the engine. Foam filters are porous and are made up of organic polymer polyurethane. This kind of foam filters when impregnated with oil traps dust due to viscosity of oil. Oil bath filters also known as Viscous filter are basically combination of paper and foam filter with a great filtration power. In these filter, a film of oil is applied on outer surface of paper. This prevent large no of particles to enter the paper allowing good efficiency of air flow while rest of the particles are trapped inside the paper and provides dirt free air to the engine.
Regular maintenance of air filter can prolong engine life with good vehicle performance. Apart from this it helps in Better fuel efficiency, Reduce emissions, Improves acceleration, unwanted repair expenses and overall improved drivability. Generally air filters needs to be cleaned or replaced at a certain time period which is mentioned on vehicle maintenance schedule but sometimes in needs to be changed more frequently if driving condition are adverse.
Now a days Oil bath filters are mostly used in 2 wheelers due to its better cleaning capacity and low maintenance.