Just a question: If motor oils have not changed substantially in composition, quality, and performance in the last few years, and engines have not really changed that much either (re:friction, temp.etc..), how can you possibly double overnight the number of miles between oil changes?
Could it be what we suspect, that frequent oil changes are the enemies of new car sales?
I do not know how often the average citizen buys a new car. I have an 86 300E with 180k. I suspect, however, that, according to auto industry marketing standards, I should have bought at least three additional cars in all these years that I kept on changing the oil every 3/4k.