Lubrication, Oil and Filter

How often?   It varies. Newer cars can go longer than older cars. See your owner's manual for details. In our opinion, the proper drain interval is determined by sampling, using spectrographic analysis. Optimal drain intervals vary from individual to individual. Accurately determining your ideal oil change interval may require analyzing the oil several times over the course of one to two years (with an additional cost of about $30 for each analysis over and above the cost of a regular oil change; see the service manager for details).

Why?   Oil is literally the life blood of the engine, but it becomes contaminated and depleted as additives are expended protecting your engine. For every 100 gallons of gas an engine burns, it makes just over 120 gallons of water, along with resins, varnishes, acids and particulates. It's contamination combined with the boil-off of the lighter components of engine oils that cause oxidation and changes in oil viscosity, pour point and lubricity. Instead of a lubricant, your engine oil becomes an abrasive slurry that accelerates the wear of critical engine components. Automotive marketing people hype the idea of grossly extended oil changes, based in part on test results from test tracks and taxi fleets. The truth of the matter is that these conditions aren't real-world for the vast majority of car owners . . . most people shut the engine off once in a while or start it during the winter!