Cadillac running at 228 degrees to 240 in traffic. Will putting a cold thermostat correct this problem?

A number of things including a stuck thermostat, low coolant, or a faulty water pump.

It really runs hot within a minute of starting ?
An engine that runs hot in a few minutes is often having problems with the water pump or a blockage in the cooling system. The thermostat does not open until 195 degrees which takes 5 or 10 miles of driving.
During that time, the water pump should be circulating coolant in the block and the heater hoses.
A leaking head gasket should be putting extra pressure into the cooling system, and-or dumping coolant into the cylinders which would come out the exhaust pipe. But it should still take a few minutes for the engine to reach the boiling point of 240 degrees.

I am guessing you have not changed your thermostat from a summer one to a winter one. If this is the case you need to put a 195 degree thermostat in to replace the 165 degree summer one. Let me know. Thanks.

It sounds like you may have a stuck thermostat or a water pump with deteriorated cooling fins. Also did you burp the system properly?

completely normal those readings are perfect this car comes with a 195 degree thermostat,210 is fine for stop a go traffic remember a cooling system with the proper amount of coolant in it and under pressure will not overheat till about 240 degrees your in great shape no conerns!!!!!...

The fans should come on at 225.and when the ac is on.

The normal coolant temp should be around 200-215 degrees.
The cooling fans will come on at around 225-228 degrees.

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

really sounds like your elevtric cooling fans are not working let it run in your drive way with hood open for a while and see if they ever come on they should come on somewere between 210 to 220 or so,[not exact specs just around there]

The cooling fans will not come on until 225 degrees. Normal temp is around 199-215. Sitting still in traffic most will inch up around 220 or so. When you turn ac on it turns the fans on and may cool down engine, Check fan operation.

Reverse flush the cooling system and put in fresh antifreeze to -20. (20 below zero). If that doesn't help, replace the thermostat.