I'm a relative newbee to boat ownership (3 years now). I know the basics when it comes to lower units (ie: how to change the oil ). So last fall when I changed it the oil was milky. I know that means there's a leak and probably a bad seal. I don't have a ton of experience fixing that stuff, so I took it to "a guy" who said he changed the lower unit seals, pressure tested it, etc. Went to change it again yesterday and it was very milky white again with some metal shavings on the plug. We don't even use our boat that much (maybe 6 to 8 times per summer). It is an older motor: 1999 Johnson 135 horse. Questions: Is it common for this to happen 2 years in a row? Could it be leaking from a different spot this time? What do the metal shavings mean? I know I'll have to get it in next spring to be worked on, but what am I looking at here?