I have twin inboards 305 Chevy Mercruisers . During an oil change we took out a total of 4 gallons of fluid from both engines. I assume it is gas getting into oil . How could that happen ? Could there be a breach of the diaphragm that is letting gas through to the oil ? Also , If I have to replace the fuel pumps do I have to use the same pump with the glass bowls attached to them ? Or can I do away with them.