These little beauties are marvelous… that blog you’ve starting following, the one with the cool info and stimulating commentary. You following me here?

Designed to remove destructive contamination from oil, filters have several components:

Tapping Plate– This is the proper term for the top of the filter where oil enters and exits the unit
Filter Medium– The main component doing the work here. Three kinds are available, cellulose, fiberglass, composite.
Center Steel Tube – This is the highway the oil takes back to the engine after filtration. The hole locations, number of holes and size are engineered to ensure proper flow.
Anti Drain Back Valve – Keeps oil from draining back into the filter when the engine is not running
Relief Valve – Cold oil can be tough to filter, so this valve opens and allows oil to flow through the center tube prior to the oil warming.

For a more in depth look at the anatomy of oil filters, check out this article by Machinery Lubrication.