I started a new topic, a segue from the "recall" thread, because thread comments often wander far afield from the original topic heading; information is sometimes missed/overlooked because the topic heading doesn't necessarily reflect the content of the subsequent postings in the thread. ;)
Oregon DOT does a good job (far better than California, IMO) of providing current road condition information; check the real-time road cams to see the situation. No, the "black ice" (scary stuff!) isn't visible on camera (or on the road, hence the name!) but one can get a general idea of the surface conditions from the road cam.
http://tripcheck.com/Pages/RCMap.asp
When I've driven Siskiyou Pass (and other passes) in the motorhome (or in a car) in winter, I travel over between midday and mid-afternoon, assuming that it's not actively snowing or storming and if there are no chain requirements. Traveling after the ice and snow has hopefully melted off the roadway a bit (be very careful of the "shady" spots!) is safer.
Of course, if the road condition is dicey, there are chain requirements, or there are lots of places to take in the scenery very quickly on the way up or down, I wait or take another route, if available.
As ever, YMMV.
Joan
And continuing on the California side:
Caltrans District 2 -Northeastern California (http://www.dot.ca.gov/dist2/travelmap.htm)