The use of a 16 lb cap will not interfere or has nothing to do with a recovery system efficiency. The caps used on a recovery system have different design tha non recovery caps. The have in addition to the outer sealing seal a center floating type pressure sealing disc that as the coolant cools and creates a vacume in the radiator/cooling system and it opens allowing to coolant to return to the radiator tank. That is why the hose or tube to the recovery tank must reach nearly to the bottom of the tank.