Only starts cold
 

My 6.0 seems to only want to fire when cold, whats the issue?

It's homesick for Canada.

Possibly a leak in the high pressure oil system, cold oil will build pressure faster than warm oil. A co worker had an issue like this with his 6.0. Ended up finding out his oil cooler was plugged so his oil was running hotter than normal. It kept eating the o rings on the oil system