Big Brake kit - fluid question

[attim]

Planning to install front big brake kit in a month or so (after delivery).
For the brake kit it's recommended to use DOT 5.1 fluid but as far as I know SAAB recommends DOT 4.

Is it possible to fill whole brake system with DOT 5.1 safely ?

[MI-Roger]

Do a full flush just to be sure, but the two fluids are compatible.

DOT 5 is a completely different fluid and NOT compatible with either 5.1 or 4! There are conflicting opinions on whether DOT 5.1 is a real improvement over DOT 4 but I can't remember why.

[sleeper9kt]

Originally Posted by MI-Roger

Do a full flush just to be sure, but the two fluids are compatible.

DOT 5 is a completely different fluid and NOT compatible with either 5.1 or 4! There are conflicting opinions on whether DOT 5.1 is a real improvement over DOT 4 but I can't remember why.

Dot 5.1 is 100% compatible with DOT 4. But, as noted don't make the mistake between DOT 5 and DOT 5.1, they are very, very different.

DOT 5.1 has a higher standard boiling point than DOT 4, but is otherwise the same type of fulid. If you don't do a full flush you aren't going to see the full bennefit of upgrading to DOT 5.1, but you can still mix them with no problems.

Myself and many of my local Saab buddies have been running DOT 5.1 for a few years now due to our cars seeing some brake abusing track time.

[Kermit]

I ran DOT 5.1 with Goodridge lines for a couple of years, it certainly firmed up the pedal response.

[karmat]

This article has a lot of good info and explains what the difference is between Dot 3/4, 5, and 5.1:

http://www.american-auto-club.co.uk/...ask=show&id=70

And this thread has good info about the respective boiling points of various brands of brake fluid:

http://www.advrider.com/forums/showthread.php?t=139701

Hope that helps

Karl