Originally Posted by jpblue

Oil pumps run such tight tollerences that any particles of dirt, metal , etc leave score marks along the mating surfaces. these are easily seen when you pull the top cover off. As well as looking at the pump side of the cover, a worn pump will have left score marks on this side of the cover. As more crap grinds away at the pump the tollerances grow and the preassure drops. The impellor? and housing are such complex shapes that reconditioning would be costly, to the point where replacement of th ehousing and impellor equals about 90 percent of the whole thing.
Going dry sump in my opinion just adds ever more complex items to go wrong.
cheers,
Justin P