Oh no, you needed to hear it. I know what your talking about with the inherent rattle, this was night and day comparatively. I took it to the manual transmission shop to have them listen and he cringed. It didnt rattle until I swapped that bearing. I run Royal Purple.
I just got off the phone with Redline. Their GL5 oils contain a brass inhibitor that makes it non-corrosive to brass, bronze and some other metal that I cant remember. Syncros are safe. But, they said that it would be too slippery for a syncro transmission and recommended MTL.