Thinking more of you than the car but you should try to get some heat going
in there. I don't recommend setting the car on fire while you work on it
but there are portable heaters that are relatively safe.
I think I might be reluctant to torque headbolts in very low temps (well below
zero, for example) if there is a way you can avoid it. Steels exhibit a
ductile-to-brittle transition at below-zero temps and the temperature where
this happens varies widely. During WWII it was responsible for a number of
"Victory ships" breaking up at sea. Since then steels have gotten cleaner
and better but you have to get special steels to have them guaranteed still
tough (ductile) at -75°F, for example. I would expect Volvo to be better
than most in this respect, but if you can warm it up even to freezing you
will be doing yourself a favor all the way around, I think.
Sure glad it's not me!! Although our nice Indian summer with temps
in the 60s ended while I was in church this morning. Went in my
shirtsleeves and was really chilly going OTL 2½ hrs later!
--
George Downs Bartlesville, Heart of the USA!