hello, I just picked up my boat from mechanic and they told me it looked like there is a leak at the core plugs (aka greese plugs they said). The motor oil is not milky, and when they started it up, there is no visible water leaking from them, but there were water spots around them. I wash my boat after I take it out of the water every time, could water from washing caused this? If there is a problem, any idea how much it would cost to replace? It is a 3.0 mercury (2002) in a glastron ski boat. They mechanic wasn't there to say if he would have to pull the motor out to fix it or not. Thanks for you help.