High Oil Temp

My oil temperature started overheating (around 233). I don't know what temperature it was before the overheating issue started, but it was definitely not this high.  It turns out I had a radiator leak. One of the thin tubes in the cooling area of the radiator had cracked and was the cause of the leak. I have to admit I flew it several times trying to figure out what was going on. It did not seem to be leaking badly. I replaced the radiator, used coolant Dexcool 50/50 mix, changed the oil, oil filter, gas filters, spark plugs and cleaned out the oil sump.

My engine continues to overheat (233) during level flight, RPM around 4800, outside temp 60 or lower. (Same temperature as before replacing the radiator and oil.)  I am flying in the northeast where temperatures are fairly cool here this time of year (50-60 F). I bought the gyroplane in Florida in March and flew it up north. Never had an overheating issue in the hot Florida weather or the the summer in NJ.  

I am new to Rotax engines. My gyroplane uses a 914 and has around 150 hours on it. Engine is in a pusher configuration. See attached photo. 

Some questions:

How do I tell if I have an coolant system problem or an oil cooling problem. 

What do I do to measure coolant temperature? Is the CHT the appropriate gauge for measuring if the coolant system is working properly. (note that the CHT never indicated high temperatures when the radiator was leaking.)

Do I need to purge the oil system? If so, what are the tricks and where is a good video for learning how to do this. 

The big question is why is my oil overheating in cooler weather with a new radiator. 

Thank you for your help!