I seriously doubt the synthetic DOT 3 caused any damage. It's basically the same stuff just "better".

I think you hit the nail on the head with the following:

1: Wheel cylinders are 15 years old
2: Truck sits around for months in the winter and weeks in the summer without being used.
3: When it is used, it's not getting a real workout.

Vehicles don't like sitting around. Rust and corrosion forms, rubber dries out, etc. I'd either rebuild your existing wheel cylinders or install new ones.


1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)