There is a good possibility that there is an air pocket in the cooling system which doesn't allow the full amount of cooling and when you have an air pocket it superheats and the fluid around gets super hot as well. run it, refill it, idle it refill it, keep doing that to make sure you have the capacity. If that's not it reading the rest of the responses on here I would say you have a headgasket seeping. Just because the oil isn't creamy or steam isn't coming out the exhaust doesn't mean it's not seeping. If it is a small leak directly at one of the cylinders it will cause a hot spot on that cylinder. The same thing happened with Spoolins car when he couldn't figure out why the temp would run up high. Good luck and let us know if you get a resolution.