When I put all new brake system parts in my 54 Suburban, I used DOT-5 (after checking with rubber-hose, wheel-cylinder, and master-cylinder vendors about compatibility). It works fine and has had no problems (except for a dirty/oily/greasey interior of the new master cylinder that was incompatible with the DOT-5 fluid).
The 54 pickup that I am restoring will also have all new brake system parts but it will get DOT-3/DOT-4 brake fluid. I figure why waste the money, why worry about compatibility with rubber parts, and why worry about silicone contamination in my garage (where I paint). I will take 30 minutes a year to bleed the system when I change oil/filter (in the fall, before winter hibernation).
