A friend had a yank 4k that wasnt stalling correctly. Sent them an email and said it was a result of the royal purple. He put the new gm dextron in and the stall is perfect now. My stall speed is lower than it should be...any fluid recomendations.

 

Thicker fluild will increase coupling and reduce stall while increasing efficency , Thinner fluilds will have the opposite effect .Type F is thinner and I have heard of people using it , However It does not have friction modifiers so unless PWM is disabled in your trans you could get converter clutch shudder with it.