Hot climate and track proven transmission oil - Redline, MotorCraft, Amsoil?
 

What are the latest recommendations for 5 speed (stock power, hot climate/track/auto-x)?

I know previously the most recommended were:
Ford Motorcraft
Redline MT90
Amsoil FGR (kind of hard to find)

and back in the day Emillio recommended adding 2oz of GM limited slip additive #1052358 to any trans oil. Does this till stand?

I used to use RL MT90 in my 5 speed but it would begin to feel notchy and generally grainy/rough feeling after 2-3 events. It's not common and can be hard to track down at times but I've been using Dumonde Tech Gear 9 for many years.

It seems to thrive off heat and abuse.