In reply to # 1492300 by mcoomey Thanks, Barry and Randall. Now I've got more info on brake fluid than I would have guessed existed and I'm sold on the DOT 5 Silicone. It's strange about the brake switch, though. I wonder if anyone is looking into that.I've looked at it a little bit, on my cars. Not sure exactly how, but it seems that somehow, a tiny amount of silicone is working it's way past the diaphragm inside the switch, and fouling the contacts. I've heard that it doesn't happen with some switches; but all of the ones I have tried (including the original switch on my previous TR3A and a replacement for a Ford truck) have failed. The failure is kind of insidious too; seems like it just keeps taking more and more pressure to operate them.
I finally solved the problem by converting to a mechanical switch. On the 3A, I mounted the switch to the pedal box, ala TR4. That car was strictly daily driver, so I didn't worry about what the engine compartment looked like
With my current TR3, I wanted a more stealthy approach (plus I wanted to keep the original adjustment screws on the pedals), so I made up a bracket to fit a switch under the dash. (Obviously still not a show car, but it might be someday.)
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild