Lancer trans

Type F has a microscopic abrasive that makes the valves in a Ford self-cleaning. It's needed because Ford didn't use filters; only screens. Steel valve bodies can take the trash a lot easier than aluminum valve bodies because metal particles only scratch grooves in the valve bores, but in aluminum, the particles plow a furrow; not removing any aluminum; but instead, raising the metal on both sides of the groove; effectively making the bore smaller; sticking the valve.