Don,
That does make me a little nervous. Makes me uncomfortable when they change back and forth like that. I'd prefer they'd "Keep it Simple". Is there that big performance difference between 4 & 5?
Ed
Ed, the important differences are the higher boiling point of silicone based fluids, that they won't hurt paint and that they entrain air in the liquid. Short of boiling the fluid you and me as drivers won't "feel" any difference in the pedal. We're just not that finely calibrated. I know of a couple of old car buddies who have made the jump from DOT3 or 4, flushed systems, etc etc etc and went to DOT5. Some swore they could "feel" a difference. Mental gymastics to justify the efforts. It (DOT5) really is good stuff. It can just be a real pain to work with.