From the owner's manual:

14 To 50 F  »  20W-20
-4 To 59 F  »  10W-30, 10W-40
32 To 86 F  »  30
Above 14 F  »  20W-40, 20W-50
Above 5 F  »  15W-40, 15W-50
Above 68 F  »  40
Below 14 F  »  5W-20, 5W-30
Below 23 F  »  10W

The manual also points out that the very light weight oils should not be run for long distances or at higher operating temperatures.  Looks like 10W-30 or 10W-40 should fit your winter conditions.  I take the above table to mean that an oil should not be used outside the ranges specified.  From experience, I do not think either 20W40 or 20W-50 works well at the high ambient temperatures I experience (above 98 F), though the table suggests it would be ok.
mcneely

---- Bob Anderson <ROBERTANDERSON294@COMCAST.NET> wrote: 
> The temps here in Massachusetts have been dipping down to single digits at night and I'm wondering if maybe I should change out the 20/50 oil I have in my 2.1 Wbxr? And, if so, what would be the recommended winter oil weight?
> Thanks,
> Bob A
> '86 GL

--
David McNeely