I have a 1962 Pontiac Grand Prix with the dreaded 3 speed roto hydramatic transmission. It works fine but I have to let the car warm up for 5 minutes before I can get it to shift. I heard the the seals are dried out and that the seals need to have a selant additive added to it to keep the pressures up so it will shift better. I did not know what the best transmission sealant out there that will soften the internal seal and prevent leakes and keep the pressure up in the transmission to stop my shiffting problem.