'Also he described the gold pump having 'marginal' scavenge capacity, hence should have a regular refresh .' Not convinced about the above quote as the Gold pump would pull all the oil from the sump and regularly gurgle as it sucked air. It also had the capacity to stop oil from draining from a cracked sump, on turning off the engine after a 60 mile drive oil poured from the crack. The Purple pump however may be 'marginal' hence the introduction of the Gold one.