I am not sure on the location of the stock sensor. I am using a defi oil temp sensor in the front oil galley on the top of the engine. Your current temperatures are fine and will not be improved much by a larger radiator. The larger radiator just has a better ability to shed heat. If you really want to buy something I would get an oil cooler. The mishimoto oil cooler i use is thermostatically controlled. Oil Temps have never been below 180. Even driving in 20 degrees f in the mountains .