Welcome to the family man. I have an '86 comp, same engine and trans. I'll have to check the oil to make sure I have it right but I am running Rotella and the trans is DEX III. As far as the whole cooler morning temps go, I wouldn't worry about it too much. Once the temps start warming up for the season in early April, I usually wake the boat up for the summer so maybe wait until then. On a side note, where you at and where you planning on boating?
'86 Comp TS6M - Reborn 2016
Riding a HO Sports CX Ski