The automobile engine’s oil filter is critically important to the life of the engine. The oil filter captures and holds contaminants and other wear causing particles suspended in the engine oil thereby preventing abrasion and prolonging engine life. The material used for the filter ranges from traditional cardboard/ cellulose/ paper types to completely synthetic which are far superior and long lasting, as well as impact the efficacy, durability and cost of the filter.
Efficiency of Oil Filters: The extent to which small particles can be captured. The most damaging contaminants are found in the 5 micron to 20 micron size range. As per the standard ISO 4548-12, a pleated paper oil filter averages 40% efficiency at 15 microns i.e. 40% of contaminants in the 15 micron range are captured. Whereas a paper/glass fibre blend averages 80% efficiency in the 15 micron range.
Capacity of Oil Filters: The volume of contaminants the filter can hold before its efficiency drops.
Types of Oil Filters –
- MECHANICAL – Made of cotton waste or pleated paper, the entrapment of contaminants reduces its efficiency and it requires periodic replacement of the filter element or entire filter.
- CARTRIDGE OR SPIN-ON – The cartridge type has a replaceable element construction inside a permanent housing, which is connected to the engine. In the mid-1950s, the spin-on type was introduced as a self-contained housing and element assembly which requires 100% replacement with a new one. But in the 1990s, leading automakers shifted back to cartridge type, because it generates less waste. New retrofit kits to convert spin-on to cartridge type filters are offered for popular applications.
- MAGNETIC – Such filters use an electromagnet to capture ferromagnetic particles. Cleaning is easy as it involves wiping the surface of the magnet. Magnets attached to the outside of an oil filter or magnetic drain plugs were first invented and offered for cars and motorcycles in the mid-1930s. But their efficacy is still questioned.
- SEDIMENTATION – A sedimentation or gravity bed filter allows contaminants heavier than oil to settle at the bottom of a container under the influence of gravity.
- CENTRIFUGAL – It employs a rotary sedimentation device using centrifugal force to separate contaminants from the oil. Pressurized oil enters the centre of the housing and passes into a drum rotor. Oil slides to the bottom of the wall, leaving contaminants stuck to the walls of the housing. This has to be cleaned periodically, to prevent the stoppage of rotation of drum.
- HIGH EFFICIENCY – HE oil filters are a type of bypass filter which allow extended oil drain intervals.