Normally I do not drain the lower unit oil I have the shop do it. Today it was very cold so I at least wanted to drain the lower unit oil. When I did I found there to be shavings on both of the screws and what look to be a hint of shavings in the oil. I have run only the XD-50. Is there anything that I should do before I put oil back in to it? What type of lower unit oil is recomended for the Ficht.