560SEL power steering box leak

[emmydotnet]

My steering box is leaking slightly, making all parts around it quite wet and a drop or two each night on the garage floor. The p/s fluid level however does not seem to be dropping. I have not added fluid, and it seems like the leak has been there for more than a year now.

I have seen some posting suggesting the use of Prestone P/S fluid with STOP LEAK, and I am tempted to use it. Can you guys update me on this? Does it work on a 560SEL setup?

thx