Working on the '85 300TD (290k mi), studied posts on oil cooler lines, dieselgiant info, and I soaked the ends of the hoses with wd40, then PB blaster several times over two days.... I have the 1 1/16 wrench, and I can't budge any of the ends. I tried tapping...grunting...teeth gnashing...
The wrench even slipped over the nut; the wrench opened up a bit to slip.
What about drilling into a nut ? What about using a chisel? I'm worried about damaging the oil cooler.
Any ideas?

__________________
'85 300TD W123
'83 300D W123, Daughter's
'80 300SD W116