[This followup was posted to rec.boats and a copy was sent to the cited
author.]

In article .com,
says...
I just now drained the lower unit (after it sat for an additional 3
years since I last ran it) and the lower unit oil is a amberish/brown
color. I do realize that the limited time that I ran it isn't really
enough to decipher it is has a problem, but I'd think it's an added
bonus if it's not in terrible shape.



Part of an engine oil's job, when lubricating the engine is to clean the
engine of carbon deposits and such. Over time this causes the oil to
darken.

In a lower unit, where there is no combustion taking place, it is far
more difficult if not impossible to determine the remaining lubricating
properties of an old oil by color since there isn't combustion residues
for the oil to pick up. Some darkening can be expected from normal
heating caused by the unit in normal operation.

It would be surprising if the color of oil in a lower unit were any
color other then what you describe or the grayish emulsion resulting
from a leaking seal allowing water into the unit.

The exception would be extreme over heating of the oil in the unit,
which can cause it to blacken. Of course, if that were the case, you'd
probably know about the problem long before draining the unit.

--
Mike G.
Heirloom Woods

www.heirloom-woods.net