I reject the use of synthetic oil on the basis of cost to no advantage.
However the input bearing on my R860 is on the way out and I must say that Penrite 85/140 has quietebned it a lot, along with a whole (small) tube of Moly for good luck.
I have ordered a shimming kit from Cycleworks and I already have the bearings, so hopefully I will do the rebuild in a few weeks time.
BTW, if you ever decide to do your own work on final drive or gearbox Cycleworks LLC is your go-to for the special tools and shims. I have beeen using their special tools for a long time now and the only one that has ever disappointed was their original tool for removing steering head races, I understand that their updated tool is much, much better.