[kamikaze]

In my opinion there are two ways to get that much oil. Lower unit is leaking ( view lower unit oil for water intrusion and then pressure test it to verify fix). or your exhaust manifold is purging all the oil/ carbon that had built up in it. I asked about the oil being used as I have found significant oil purging from the exhaust after overheating a engine if the oil has a decarb / cleaning additive. And the oil you show is more grayish than rainbow stained indicating he oil has already then burnt. I agee with Phat, Pull the spark plugs to verify no water intrusion in clyinders after head gaskets install (will also purge exhaust). If not and the lower unit pressure checks go run it and see if it cleans up.