The best type F is the synthetic version of B&M Trick Shift
the 2nd best is the conventional B&M Trick Shift
These products are NOT additives, but a stand alone type F fluid.
Z
PS. The above reccomendations are applicable to the fluid choise in the vintage ball drive Paxton supercharger.. my last Paxton had 75,000 + miles on it with ZERO maintenance other than changing the synthetic B&M fluid fluid at every oil change. Numerous high speed endurance runs on the course of the Big Bend Open Road Race, 53 miles each way @ maximum rpm 95% of the time. A fluid cooler was also installed. If you have a Paxton this is the way to keep it from wearing out. At the time I sold the Paxton, I sent it to Craig C to have it checked out. He reported it had no wear and needed nothing.