The issue with alumimium engine blocks and steel oil control rings is wear and compensatory oil loss. due to vacuum increase. Psychos is right to alleviate the suction problem via breather application. But you also need to make sure the engine is sealed up tight in the first place. Said differently, make sure the oil filler port is closed tight. Make sure your filler o-ring is in good shape or replaced every few years. If the systen leaks at any juncture it will cause the engine vacuum effect to be magnified and the PCV will remain open when it should be shut and oil will be sucked in and burned.