Is it better to plumb cooler so hot oil goes into cold side of cooler or sea water exit side and why.
Nordic95

I ran mine so that the hot oil would be flowing in the opposite direction of the water flow through the cooler. Does it really matter??? I would say it could make a difference if your cooler was barely capable of cooling the oil due to performance upgrades. If you have a large efficient cooler it probably would not matter. Just my .02

I was thinking of plumbing the same way you did.I figure it is better to let oil cool as it travels towards cold water side.
Nordic95

Yes, common practice is to flow oil opposite of water flow. This is refered to as counter flow configuration versus parallel flow configuration.