Just my 2 cents on the "C" drive and seals.
My oil reservoir is labeled "15w40" and I've read the same in manuals. The 15 rating means that it is thinner at lower temperatures (when you first start up) but retains 40 weight protection at higher temps.

In earlier postings there is mention that Amel went to 1 seal facing inward (toward the oil) and 2 outward toward the sea water. This is because there is more often a problem with sea water leaking into the system then oil leaking out--although both are possible in severely worn or damaged systems.

A key to keeping the stainless lip seal springs from corroding is to pack them in grease. I have had very good luck with the grease that is marketed for packing the wheel bearings of boat trailers. It is designed to keep sea water from permeating and causing corrosion. It is also designed to withstand high rpm and temps and to avoid being washed away by sea water. It is inexpensive--usually blue and green in color and is marketed as "marine boat trailer grease" .

Bob
Brittany de la Mer