Good article, I agree with just about all of it. He actually confirms my belief that the very long change intervals aren't good for a motor, as with Amsoil. I run Mobil 1 almost exclusively in my cars, and I run them to about 5K between changes (using regular Mobil 1, not the EP). Amsoil advertises change intervals up to 25K depending on the grade you use, which I think is crazy no matter how good their product is. I know they tell you to make sure you are changing the filter every few thousand, but a filter does not remove acids, moisture, fuel, phosphates, and sulfur, all contributors of sludge.