| That quote was from a Yoyodyne Brembo FAQ page that has been deleted. I think that it was Yoyodyne's assessment of the issue, not Brembo's.
Most everyone will tell you not to use DOT 5 in brake systems that already have had DOT 3 or 4 in them. It's true. When you mix a glycol-based fluid with a silicone-based fluid the mixture coagulates and piston-retraction problems occur.
What they don't tell you is that you CAN do it if you completely disassemble the brake system and clean it thoroughly with denatured alcohol. Also you really should replace all the seals. You can however soak good old used Brembo seals in alcohol for several days (renew the alcohol daily) and then re-used them in a DOT 5 system. The optimum situation is to only put DOT 5 in a new system that hasn't seen glycol.
One owner of a '90 851 and '93 888, both having Brembo brake systems (master cylinder and caliper), reports that he has had DOT 5 in them for 10 & 7 years respectfully (after flushing and refilling) without a problem.
So, if it really is a seal/fluid materials issue as Yoyodyne has previously suggested then how does flushing help? Direct experience indicates that it is not a seal compatibility issue but one of what happens when these two brake fluids mix.  |