"If your boat is winterized co
"If your boat is winterized correctly, a tune up is about all you need to do. New plugs at least.
That is a Mercruiser 470 isn't it? It should have a closed cooling system and all you did was drain the fresh water out of the heat exchanger. The lower unit needs the lube checked but if you are sure this was done on winterizing and there are no leaks you should be OK. Spring is a good time to remove the outdrive and grease the universal joints, put in a new water pump impeller and possibly a new water pump housing if the old one is scored badly. Remove the prop and grease the prop shaft."