I went out the other morning and it was about 42 degrees. For a temporary "fix" I just quickly cut out a piece of card board and put in front of the
oil cooler. After driving for 5 or 10 minutes, the
oil temp did come up to about 90C (194 F). Thinking about it, the plexiglass idea is a good one. Obviously would block more wind than cardboard and would certainly look much better.