Hence, the name anitfreeze. I wonder how they came up with that?

Sorry, couldn't help it.

 

The engine needs more cooling on the highway.

Does your new fan clutch roar the fan at about 40 to 50 MPH?
IT should.

Have you taken a hose and squirted water back to front thru the oil coolers and the a/c condenser - you should carefully and use degreaser on these.

Is your AUX fan working or frozen? An Aux fan which is working and even OFF will let more air through as the wind will spin the blades. The frozen fan will block air.

System must be fully purged of air.

And run Premium gas! If you are running regular you may be getting extra heat from
the knock sensor running the engine timing retarded.

 

Just finished changing out the factory thermostat with the geniune Land Rover Warm Climate 180-deg thermostat (gray version).

Engine is 82K running on the original head gaskets.

50/50 mix Service Pro non-Dexcool (yellow).

Here are my temps using my ELM327 Bluetooth OBD and Torque Android app.

 

I live in Hawaii an my ambient temps hover between 85 and 95, and in stop and go I usually sit between 194 and 201, and on the highway I can get as low as 183, but it generally sits 186 to 190. 215 isn't too bad I suppose, but 216 is my "overheating" alarm setting on my UG. It has saved my butt a few times.

The 180 T-stat dropped my temps quite a bit, and if you haven't already, take the time to put one in.