Thanks for the advice, but I’m already sold on the product.  A mechanic friend, who works on expensive European cars, gave me a few ounces left in a bottle to try.  I put it in the power steering reservoir of my 1965 Humber Imperial, which leaked fluid from multiple places in the ram and at the pump.  I kept a catch pan under the car which needed frequent cleaning, and the reservoir needed topping up before each use of the car.  I had accepted it needed a rebuilding of the ram, with likely unobtainable new rubber seals.