Max retarder temps?

[Ryan Wright]

Jerry's post about his first loaded trip reminded me to ask this question:

At what point does the retarder temp become a concern? What's the
magic number I need to keep it under to avoid problems? The red line
on my gauge is @ 330 so I stay well away from that, but Jerry's post
sounded like 260 was bad and that's always seemed
middle-of-the-gauge-ok to me.

-Ryan
'86 PT-40 8V92