Here's an article that will interest everyone who owns a car. Car owners often hear conflicting advice as to how often one should change the oil in their automobiles. This piece explains why the old standard of every 3000 miles is no longer applicable:
For years the accepted oil change interval (as per the carmakers) has been every 3 months or 3 thousand miles, whichever comes first. Why? Because the oils of yesterday degraded and broke down when left in the crankcase environment for longer than the prescribed interval. The combination of heat, friction, and the oil oxidizing over time resulted in an unholy clothing of the engine's internal parts called sludge.
As an automotive machinist for a good part of my career, I can tell you that sludge is an engine killer. Sludge takes a greasy, cake-like oily form and plugs oil return passages and acts like a sponge and soaks up good oil to grow its grotesque form starving the engine of vital lubricants.
Once established, engine heat crystallizes it to a hardened rock of ughhhhhh, I have spent many an hour scraping and yes, sometimes chiseling established sludge from the inside of an engine before performing a machining operation on it! As the machinist prepares to perform a machine operation on a cylinder head, crankshaft, engine block or the likes he/she must clean their work meticulously before performing the prescribed operation. If the sludge is not cleaned properly, the result will be a failed engine.
Why this lesson about sludge? Because without clean good quality oil in your car's engine, it will develop sludge and cause premature engine failure.
Go to the link for the author's recommendation and his rationale for it.
RLC