DOT 3 vs. DOT 4

I got my new master cylinder today and a new problem arose. The master says use only DOT 4 fluid. The old system was DOT 3. Will the old line and caliper function with the DOT 4 fluid? I did a general internet search and found that the basic formulation is very similar with an additional compound added in to the DOT 4. Does anyone know more about this than I do (I assume someone does 'cause it won't take much)?

Nick

Post edited by: Sputnic81, at: 2006/04/21 02:02

DOT 3 & DOT 4 are compatiable with each other, so you should not have any problems. That said, I would still pump enough DOT 4 thru the system to purge all of the old DOT 3 out.

Post edited by: Murphyau, at: 2006/04/21 05:40

Got the new DOT 4 in. Brakes are nice and firm. Should be all licensed, insured and ready to go by the end of next week.