Tom, thank you for your comments concerning the PCV info at the First Coast Club site.
I'm not convinced that crankcase pressure is my issue, as I don't have other symptoms like
oil blowing through breather cap or dipstick. But not saying it couldn't be contributing to the rear seal leak. One has to choose which rabbit holes one wants to go down...
Will look at PCV valve and see if maybe it needs to be cleaned (duh!). Was mostly inquiring about the Blue Devil product to see if others might have had experience with it. Just would like to eliminate the rear seal leak mess, if possible...