"For years the accepted oil change interval (as per carmakers) had been every 3 months or 3000 miles, whichever comes first. And why was that? It was because oils of yesterday 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."

That's an absolutely insane number, and I have never heard of that (I have had cars for 20 years that always were 10k to 15k km intervals, and simply done on a yearly or 18 months service).