We took our SW through in August 1995, following Route 190 heading 
east to Las Vegas. It was just a drive by, all done in the hottest part
of
the day. The temperature was 106, if I recall correctly.

Engine was fine, though we turned off the air conditioning and opened
the windows whenever the fan went kicked into high speed, which happened
on the long uphills. CV joints started making little knocking noises,
though, as the grease thinned out. I was relieved once we got out of
there....

Gerry has posted my trip report with  the details at:
http://www.med.umn.edu:8853/misc/archives/Files/Trip-Report-Oregon-to-Ma
ryland