Got my second certified oil analysis back using the Amsoil air filter. I had 5260 miles on the oil using the Amsoil dual air filter oiled at the factory. The driving conditions were very good as there was no blowing sand, dirt etc for this test. The tech was probably right in that I had a lot of crud left in the engine block during the manufacturing process that gave me higher contaminant readings on that first test. That being said, this test still gave higher readings in contaminants & wear metals than a good paper pleated air filter. My silicon level was 11ppm on the contaminant side while the iron reading was 9, lead was 1, aluminum 2, nickel 1, copper was 10 and chromium was 0. The copper reading is from the oil cooler having a copper core. Should be very low in another 20K or so. Compared to a good pleated paper filter the Amsoil allows 3ppm more silicon contaminant (dirt) into the engine resulting in approximately 1 or 2ppm more of iron as a wear metal. I base that on other oil analysisÆs I've had done from my Sequoia's oil.