What kind of Transmission Oil for TD?

[Robert J Donahue/DELCO <RJDONAHU@mail.delcoelect.com>]

I've been following the controversy about motor oil v.s. gear oil
in the MGB. Some have warned about gear oil eating brass
parts. Would this apply to the T series cars? I've been using
common Valvoline SAE 90-140 rated GL5 in my TD. Am I being
paranoid? What are you other T owners using in your
transmissions?

Bob Donahue, Still stuck in the '50s
52 MG-TD, under DIY restoration
71 MGB, still in the shop, 11 months and counting