For some parts in the trans, it would be great. I would love it !
But I do NOT recommend this! The synchros can permanently be made to be too slippery - draining the fluid afterwards will not cure it - the moly is impregnated and bonded with a sulfur bond.
Some people have been lucky. And if you have aggressive synchros, you can get away with it. But it is counterproductive in this critical area.
Don't put moly in a manual trans.