Gearbox oil Montecarlo

[Otto-valvole-per-tutte]

What oil can be used?

http://www.castrol.de/produkte/a_auto/b_getriebeoele/index.html

Isn't ZC90 the original specification?

Should i use a full mineral oil?

Cheers for any help, Pieter

[Will]

Here in the US, the most popular choice is GL1, some difficulty obtaining it as it is mostly sold in bulk, through farm equipment dealers.
Some swear by Redline MTL or MT-90. I like MT-90 personally, this can be mail-ordered in quarts. I get mine from an oufit in CA, ioportracing.com.
Some even use heavier weights of motor oils in the gear boxes, I guess it's mostly a matter of personal preference.
The general consensus is to stay away from the "EP" (Extended Pressure) oils designed for boxes with hypoid gears. Apparently, this can overlubricate the synchros and cause balky shifting.
I'm just parroting this, as I don't know sh*t about gearboxes, never even disassembled one (keeping fingers crossed)!
-Will