Got a couple of the hydralock units I'm thinking of using on some retracts. The directions say to use either transmission fluid or low vis refrigeration oil. Wondering if anyone has any experience with these. They were sold by sonic-tronics and don't know if they are made or sold anymore.

Hello, I had set in a TF P-47 they work very well but were a pain in the you know what, to put the fluid in and make sure of no leaks. In the long run it was worth the effort. Now I use the adjustable air valve which will do the same thing without the mess IMO.