I posted this in diesel discussion, but I want the best chance of getting some help so I'm posting here too.
I am in the throws of changing my oil cooler lines, motor mounts and engine shocks & mounts. The car is up on the jack stands, I'm ready to jack up the motor via the oil pan. I went to loosen the 8mm hex bolt under the left mount and saw it was already rounded out a bit. I sprayed it with PB blast and let it sit for a while after tapping on it. I tried to apply some heat for about 20 seconds and tried turning it which finished rounding out the hex bolt.
How should I go about removing this bolt now? It looks like tight quarters for whatever the solution is. The bolt head is accessed through a hole in the crossmember under the mount.