[Brobrian]

Wow!
I've been following this whole discussion for days now and have included that we have two types of recommendations: anecdotal and technical. There are stories of what has worked or not, and there are technical recommendations. I guess I'll have to choose between keeping the "not recommended" Lucas Hub oil which has indeed quieted my gearbox and made shifting easier, or mixing Lucas oil treatment with 90 weight gear oil as prescribed above.
BTW thanks to all you petroleum experts for your contributions. I had no idea so much science went in to matching lubricants to their applications.