As Stirling stated...I wonder if there's any petroleum based plastic or particularly latex in the belts. Oil will indeed rot rubber. Thats one reason why your not supposed to use WD40 on your vehicle door sills in the winter. It might solve one problem at the moment, but creates a much more serious problem later. The 2 do not play nicely together. You could buy some KY jelly for your belts.

Might wanna tell the wife what your doing before she stumbles upon a tube of KY in your toolbox, though, because yet again... It might solve one problem at the moment, but creates a much more serious problem later.

Seriously though, I wouldn't think belts would need lube. If you feel that they do, my first thought would be some belt dressing from the auto store.