i also agree your cooler should do a better job than it is doing, i know even in my boat (a little 4cyl 180) the oil gets hotter than a firecracker even to the pount that if i had my choice i would run a hi capacity pan to give the engine some thermal room.
a car has a lot of loss of heat just to the air moving by the pan as opposed to the basicly still air in a boat compt.