WHat if Hitler wasn't a completely insane kleptomaniac and had allowed Paulus to break 6th Army out of the trap at Stalingrad and been able to link up with Manstein's Army Group B with the sole objective of taking the Causasian oil fields? Could the Nazis still win the war at that point?
Manstein didn't command Army Group B; he commanded Army Group Don; B was still commanded by Weichs.
Without other POD's Paulus' only chance to breakout was immediately once the Soviets linked up at Kalach. He could have massed his forces (in conjunction with relieving attacks from the north and south that would have had to be arranged) to overwhelm the relatively small number of Soviet units on his southwestern supply lines; once his troops retake Kotelnikovo and his supply lines are reopened, he can conduct a slower and more orderly retreat back to the Don, carefully screening army group a's withdrawal
Otherwise, not happening without other POD's