I’ve been running synthetic in my 2.1 Boston Bob since I had it installed about 15 years ago. Before that in my old 1.9 I would run 20w/50 from spring to fall before it would get parked in the winter. Wondering what weight I should use for synthetic with temps ranging from about 15C (60F) to 35C (95F). I believe my garage has been using 15W/40 but wanted a third opinion :)

Thanks
Jeff
85 Westfalia GL on engine #2
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