I have a simple question, is it okay to mix different brands of silicone brake fluid? I recently had some work done om my '66 coupe and the mechanic added Quaker State silicone brake fluid (yellow color) with the North American silicone brake fluid (purple color) currently in the brake system. I hope this does not present me with any problems. Thanks for the feedback!
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Re: Silicone Brake Fluid
John:
I believe that all DOT 5 (silicone base) brake fluids are compatible. I would just make sure that the fluid the mechanic used to top off was, in fact, DOT 5. All the DOT 5 that I have seen is purplish in color.
Joe -
Re: Silicone Brake Fluid
John:
I believe that all DOT 5 (silicone base) brake fluids are compatible. I would just make sure that the fluid the mechanic used to top off was, in fact, DOT 5. All the DOT 5 that I have seen is purplish in color.
JoeComment
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Re: Silicone Brake Fluid
Joe, I did the paint test last night where I dabbed some of the brake fluid in the master cylinder onto a paper towel and then rubbed the paper towel on one of the black shields and no black paint came off. Therefore, I was fairly sure the added brake fluid was silicone. However, like you, I was under the impression that silicone brake fluid is purple in color. Can someone verify that the Quaker State silicone brake fluid is yellow in color? Also, if someone was to mix silicone brake fluid with non-silicone brake fluid, I assume the two fluids would seprate and cause brake problems. I drove the car last night and the pedal and braking action seemed to be okay. ThanksComment
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Re: Silicone Brake Fluid
Joe, I did the paint test last night where I dabbed some of the brake fluid in the master cylinder onto a paper towel and then rubbed the paper towel on one of the black shields and no black paint came off. Therefore, I was fairly sure the added brake fluid was silicone. However, like you, I was under the impression that silicone brake fluid is purple in color. Can someone verify that the Quaker State silicone brake fluid is yellow in color? Also, if someone was to mix silicone brake fluid with non-silicone brake fluid, I assume the two fluids would seprate and cause brake problems. I drove the car last night and the pedal and braking action seemed to be okay. ThanksComment
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Re: Silicone Brake Fluid
John------
Silicone brake fluid is dyed purple for identification purposes. However, the dye is not a permanent one and, after it ages for awhile, the fluid becomes a yellow color. I don't know if this is the natural color of the fluid or if it's the decomposition color of the dye. I suspect the latter. In any event, the coloration change does not affect the brake fluid. If you examine the brake fluid in a car converted to silicone fluid, after a year, or less, you will find that the fluid is yellow, not purple.
If you want to further test the fluid, it's simple. Just place a small amount of it in a glass vial with some known silicone fluid. Cap and shake the vial. Let it sit for about 5-10 minutes and observe if there is a phase seperation (i.e. there are 2 discernable "layers" like oil in water). If there is a phase seperation, then the fluid in your car is not silicone. If the fluids are miscible and there is no obvious phase seperation, the fluid in your car is silicone.In Appreciation of John HinckleyComment
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Re: Silicone Brake Fluid
John------
Silicone brake fluid is dyed purple for identification purposes. However, the dye is not a permanent one and, after it ages for awhile, the fluid becomes a yellow color. I don't know if this is the natural color of the fluid or if it's the decomposition color of the dye. I suspect the latter. In any event, the coloration change does not affect the brake fluid. If you examine the brake fluid in a car converted to silicone fluid, after a year, or less, you will find that the fluid is yellow, not purple.
If you want to further test the fluid, it's simple. Just place a small amount of it in a glass vial with some known silicone fluid. Cap and shake the vial. Let it sit for about 5-10 minutes and observe if there is a phase seperation (i.e. there are 2 discernable "layers" like oil in water). If there is a phase seperation, then the fluid in your car is not silicone. If the fluids are miscible and there is no obvious phase seperation, the fluid in your car is silicone.In Appreciation of John HinckleyComment
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