Brake Fluid Question

[jcantor]

I am in the process of redoing the hydraulic brake system on the antique in my fleet ('56 Imperial) and am deliberating between using DOT3 vs. DOT5 fluid. One consideration that I have is keeping all of my cars on the same fluid to make future maintenance easier and lessen the chance of mixing fluids. Hence my questions:
Can I run DOT5 in an '87 560SEL?
I know DOT5 is available in different colors to make system flushing easier; is DOT3 also available in different colors?

Thanks,
jlc

[estrellajon]

I know DOT 5 is synthetic. I would go with the number that the manufacturer calls. I had a friend who had to replace a master cylinder on an older Porsche which the tech claimed that it was the fluid used. Who knows if thats really the case.

I didn't know that ANY brake fluid came in different colors, but it is unnecessary. Simply start flushing (bleeding) and watch for the fluid to start coming out clear before moving to the next wheel. For a really good flush, go back to each wheel again after you have gotten clear fluid from all of them in give it another good squirt or two.

I would do that car with DOT3 which is much better than what they had in those days anyway.

BTW When I was in elementary school in the fifties a neighbor friend of mine had a '56 Imperial. What a car for its day!

Good luck,

[Ron in SC]

ATE blue fluid is still available it has dry boiling point of 536 degrees F. same BP as the Type 200. You can alternate brake flushes between the two to see when you don't need to flush any further.

[Duke2.6]

DOT 5 is silicone based. DOT 3 and 4 are glycol based. Do not attempt to "flush" a system that had DOT3/4 with DOT 5. The two are not miscible and have significantly different specific gravity,and there is no way that the glycol fluid can be compelete purged by flushing. The only way to change over to DOT 5 is to take the system completely apart and start with everything new, clean, and dry, then assemble all the hydraulic components with DOT 5. The lines should be thoroughly flushed with denatured alcohol and dried and the hoses replaced.

The advantage of DOT 5 is that it does not absorb water, so it need not be flushed as often, but DOT 5 is also NOT RECOMMENDED for ABS systems.

Duke

[Hatterasguy]

MB specs DOT 4 that is what should be used. I wouldn't put DOT 5 in a 20 year old brake system, you are just asking for problems.

[jcantor]

I've seen info on the ATE fluid before. They don't seem to indicate what spec it is but I'm assuming from the boiling points that it is DOT5. Is this correct?

jlc

[Ron in SC]

No it's just DOT 4. It's just good high quality brake fluid. The container says it can be mixed with DOT 5.1

I don't use DOT 5.1 as it not recommended for any of my cars.

[Hatterasguy]

Isn't DOT 5 racing brake fluid?

[Duke2.6]

ALL brake fluids are "synthetic"! The polygycol base of DOT 3, 4 , and 5.1 are created by a petrochemical process. So is antifreeze. Polyglycols don't exist in nature. They are "syntesized" chemicals. Same applies to DOT 5 silicone based fluid.

"Synthetic" refers to virtually any chemical that is not derived from distilling crude oil - same as "petrochemical" which is anything that is synthesized from petroleum based feed stocks, which includes most of the polymers used in modern society.

Duke