Mine has not split since adding a breather to it. (to the small inner section)
As for the grease temp. DO NOT use grease that comes with the kia sedona boot. I got that turned into a liquid somehow.
So any decent quality grease is fine. Inner CV needs 150 grams. Outer CV needs 130 grams.
If you feel like spending more on grease:
Redline CV-2 goes up to 260 degrees, and is about 30 euro a jar.
NEO HPCC1 goes up to 649 degrees, and is about 170 euro per container.