I have been losing about 1 or 2 inches [ reservoir ]
of coolant in the warm/hot months per 30 days but none
during the cold/cool months. No loss since October.

This has been going on for a few years now and seems
that the 70 degree area seems to make the difference.

Is there a possiblility of small evaporation or something to that effect?
Drivetrain is fine otherwise. No evidence of leaks anywhere.
Have made no adjustments.

Any thoughts on this phenomenon?

I think these Volvo's have little idiosynchroses which are quite normal!

ty
rd 99 c70 hptm 34k