Re: Synthetic Oil
The synthetic scam:
The reason you change oil is because it gets diluted with gasoline (blow-by etc) gets carbon in it (from combustion,) and gets acidic from the unburned HC and water. Filters cannot get all the carbon out, cannot neutralize the acids, or get the unburned gasoline out (gas destroys the lubricity.)
The supposed idea behind synthetic is you don't change your oil as often (justifies the higher price.) You leave all that stuff in your engine so the carbon can wear your bearings and rings better, and the acids can eat away the bearings at the same time.
Do they care?
The only way to get rid of the carbon, HC, and acids is to dump it out!