What type of brake fluid?

[Mark IV]

Originally Posted by BBQCYCLEWERKES

not to get defensive either, but SPF 1950 wasn't around in the 60's. Common practice from 2000 and up was that disc brakes used dot 5 and hyd. slave cylinders used dot 3. I agree, to be safe, purge both systems and use dot 3 for the hyd. clutch and dot 5 for the brakes. Manufacturer recommends to flush the salve cylinder every 1-2 years anyway as that fluid for some reason always seems to get very dirty.

Actually, there are some valid reasons NOT to use silcone brake fluid. A high quality DOT 4 is sufficent. While Glycol based fluids do absorb water, silcone does not. That is not an advantage in cars that are well maintained as the glycol holds the moisture to be flushed out when changed as a high performance car should be. The silicone allows the water to gather in your caliper bores and corrode. Many people who have gone silicone are surprised to find corrosion, "I thought silcone didn't absorb water?" they say. They are right, it does not absorb water, but moisture will still enter the system and find its way to the lowest point in your brake system. Good old DOT 4 holds the water in suspension to be flushed away.....

Use a brand name high temp DOT 4 fluid for the street. Racing fluid is made to be changed often as racers do. Regardless, something like an SPF is worth a brake flush every three years or more often.