I always have heard to use lube on seals when building a motor, any motor.... So I always have. I use a touch of thick gear oil or assembly lube (something that will hang around in case I dont fire the motor right away) But then again, I used to use anti sieze on my flywheel untill Loco brought up a good piont about that putting more stress on the woodruff key. Which is unrelated but what I'm sayin is untill I see a valid reason not to use a little lube on the seals, Im gonna do it, cuz It makes sence to me.