Oil coolers are pretty tough. They are a heck of alot tougher than the radiator, as they operate at 10 times the pressure. If you are afraid that you won't notice the
oil pressure gauge going to zero, you will still hear the motor ticking like a sewing machine. As for the necessity of the
oil cooler, it depends heavily on a myriad of factors which vary car to car. If you like driving around in second gear at 4000 rpm all day, your motor has excessive thrust issues, you actually race it some, it does in fact make 600 hp, these are the kinds of factors which will determine the necessity of such.
Put an oil temp gauge on it and find out if your car needs one is the best advice.
If you want one just for looks, call around and try to get a "used and dirty" one. After a motor lets go, the oil cooler is junk as you will never get all the debris out that the oiling system depsited in the cooler. Acouple of other issue relating to oil temp: high volume oil pumps can add a good amount of heat to the oil in some situations. The motor will only flow so much oil, the pump moves more oil than necessary which is how pressure is developed. After enough pressure is generated, the bypass in the pump opens allowing the excess oil flow to get blown back into the oil pan. This secondary path of oil flow can add considerable heat to the oil which takes this path. Excess oil pump capabiblity over what the motor needs costs hp, adds load to the timing chain and dist gear, and can heat the oil up some. Depends on the motor's clearances and how quickly the oil gets slung off the crank. Pushing your motor oil through a cooler will drop the pressure some, assuming all else is constant.