Oil Temp while towing

I have an oil temp gauge that is ran to the back of the block coming off of a port. I've noticed that even while not towing that hit seems to get real close to around 210. While towing my traveltrailer this wekend it hit upwatds of around 230. That seems a little warm to me. Don't these trucks come with oil coolers on them?? I haven't gotten under to look for one yet. I just assummed it was there. I'm If I do need to add one what would be a good one that would work good while towing. My trailer is around 9000lbs when loaded down. Thanks.