Hydraulic surge brakes (drum) on Genie towable lift. Replaced wheel cylinders, rubber lines, and the surge master cylinder. They were all mucked up with corrosion. Now that everything is new I’m thinking of filling it with DOT 5 silicone fluid. Seems like machines that sit a lot outdoors would be good candidates for silicone fluid. Any reason not to do that? The surge controller docs say it is compatible with silicone fluid, not certain about the wheel cylinders. But I would think a new wheel cylinder would be compatible.
As long as the whole system is new, I see no problem. That said, DOT3 is hygroscopic. In other words it absorbs and disperses water throughout. DOT5 is hydrophobic. It repels water. So naturally any moisture will settle and collect in a low spot or dip. In the winter, this could freeze and obstruct a brake line. It would require periodic flushing to keep excessive moisture under control.