I'm a huge fan of Permatex Spray Tack. I normally use 3M Weatherstrip adhesive on the ends around the water ports.  We call it Gorilla snot because it's yellow and nasty.

You can use RTV,  I tend to only use that on the valley ends.

You can also boil the water out of the oil on a stove.  Done it on at least three occasions.

Just keep it clean and while it's hot run it through a milkscreen.

We were very broke when we were racing and could not afford new oil of we could avoid it. The gas in the tow vehicle always seemed more important lol.