I just found this great article on "Lubricating the Vacuum Wiper Motor". My motor is very stiff so I'll be just oiling using Marvel Mystery Oil, MMO, I know it is good for the leather in my Columbia vacuum canister so a good choice here.
I know that brake fluid and ATF will swell rubber and give a better seal. I'm not sure how it acts on leather which is used on the wiper motor internal paddle.
https://www.mafca.com/downloads/Tech...um%20Wiper.pdf
Glenn