Your oil filter is the last line of defense before contaminants get into the heart of your vehicle. Those contaminants can lower your engine's performance and cause costly damage. All moving parts in an engine need clean oil to function. A premium filter maintains the quality of the oil circulating in the lubrication system, keeping your engine running efficiently for a lot longer. The Royal Purple Extended Life Oil Filter 20-51A with silicone anti-drain back valves uses 100% synthetic micro-glass filtration media supported by steel mesh backing for superior particle removal. The quality of an oil filter is stated as a percentage of particles caught at a certain size or larger. Royal Purple boasts 99% filtration efficiency at 25 microns or larger, and 80% at 10 microns. We don't believe in messing with perfection, so we only produce one type of oil filter with variations for different motor vehicles.