Hey, looks like you "got milk"!!! That's is really ugly man!
I change my lower unit grease once a year (usually every fall) with a good grade grease made by OMC. Don't think you can go wrong doing that.
I also found that OMC(and maybe the other guys do to) now offer drain plugs with a hex head drive hole instead of the old slotted style. Used the hex drive for the first time the other day and the plug came out without a hitch...first time it has ever been that easy!!! I'am all for that kind of help!!
slab happy