Just fitted my oil cooler, havnt started the engine up that's tomorrows job. Now do I fo for a drive get up to temp, In theory the oil temp gauge should register as it's after the stat so when the oil is flowing down that route it should move the needle. Then check the oil and top up as necessary. or put extra oil in before which could be hard as I don't know how much it should take.
Sorry yea an external one couldn't fill the cooler first as the inlet and outlet is up at the top close to the floor but if it needs to be I'll go and get a turkey Baster and squirt it in there.