The oil cooler is design for cooling the oil. Keeping the temperature lower on the oil will prevent the oil from breaking down as fast thus longer life span of oil and engine components. The cooler oil temps will cool the engine a little. Maybe 10 degrees but the main purpose is cooling the oil. To give an example. Before I installed the oil cooler the oil would turn black before I could put 500 miles. I changed my oil a couple of weekends ago. With a little over 1100 miles the oil was a dark golden brown. Cooler oil temp also help keep the clutch cooler. No problems finding neutral once the engines up to temp.
It takes about 1/4 of a quart more oil which will be a good thing.