i switched to synthetic atf in the dead of winter... and with synthetic you start up and drive off with good performance... you could immediately notice the differnec

I avoid dot5 in anything that doesn't require it. The silicone fluid does not absorb water - which means that instead of being absorbed and dispersed throughout the system, any water that makes its way in (and it always does!) will simply pool in the low points. This is usually the wheel cylinders. At best, this just causes corrosion and the need for replacement parts. At worst, you get on the brakes hard, boil the water in there, and lose braking.

Dot 5.1 is a non-silicone fluid that meets/exceeds the dot5 temp standard. There are also brake fluids out there with boiling points over 600F if you really want to get serious. But, with street brake pads, by the time your brake fluid is at 600F, your pads are probably already toast.

Something else I have heard is that dot4 loses boiling point more rapidly than dot3 as moisture gets into it. Therefore, if you use dot4 it is reccomended to bleed the brakes more frequently.

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1971 220D/4-speed ~250K mi. Family owned (dads side) through three generations since <5K miles.
1992 Chrysler LeBaron, 3.0V6 125K. Family owned (moms side) through three generations since new.
1977 Chevy Camaro Continual hotrod project
1970 Cadillac Sedan DeVille 472ci and nearly 19' long
1974 Fiat Spider Still needs work

i never had either of those problems noted above with the silicone when used in drum braked cars. i am not saying it cant happen, but i never experienced it.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.