The resevoir in my '83SC needs topping up but I can't figure what brand of fluid is in there. It's kind of brown coloured like motor oil, whereas most brake fluid I have used in the past is a blue/green colour.

Any idea what brand it could be and do you think there is any danger mixing with other DOT3 brands if I can't match the original stuff?

Thanks.

 

The "brown" fluid probably indicates that your fluid is way past due to be flushed and replaced, or that the internal seals of the master cylinder are failing. Now is the perfect time for a brake "tune-up": (1) How old are the four rubber hoses?, (2) How old is the master?, (3) How much life is left in your pads?, (4) How thick are your rotors? Based on your answers more can be offered.
Pete

 

(1) How old are the four rubber hoses? About 8 years.

(2) How old is the master? No idea, probably original so 22 years!

(3) How much life is left in your pads? Plenty, near new from PO.

(4) How thick are your rotors? Near new, minimum wear. What is the minimum thinkness btw?

Thanks Peter!

 

Brake fluid is cheap... any doubt, change it. Mixing fluid is a really bad idea.

 

Brown is rust. time to change, period.

 

well, not rust - but it does mean you should change the fluid

search here and at Pelican to get details on how to do it and then change the fluid every 2 years thereafter

how old are your rubber brake hoses??
If > 5 yrs or if you don't know, then I would definitely change them for new stock rubber hoses.

 

If not rust, What? When I got my car some 25 years ago, there was not only brown fluid in the reservoir, there were brown particles in the calipers when I changed it. Looked like it was OE fluid or near to it. In the process of changing it, the MC didn't like being stroked below what it was accustomed to and pooched shortly thereafter. If the brown tint and particles were not rust, what else is in the system that would produce that? The MC was not leaking prior to using it to change the fluid, so i couldn't have been chunk of rubber seal. What am I mimssing here?

I have always read and been told that the brown was the product of the inside of the brake lines and/or the caliper pistons rusting from the moisture delivered inside the system from the wet brake fluid.

Have all my advisors been wrong all these years?

 

they are probably using the word rust (an iron oxide) for any oxidized chemical...

bottom line - you're right - if it's brown, flush it...

 

How do you avoid mixing fluid types absent disassembly and complete purging of all components?

 

Fluids are compatible* so it's like changing your oil -- a bit of old oil is not a problem.

*except for silicone which you should avoid

Let me harp on the age of the rubber hoses again....

 

Giant: My recommendation is to replace the master cylinder, give the fluid a good flush, and you'll be right on schedule to do the hoses and fluid in another couple of years. The minimum wear specs for your rotors are:
Front: 18.5mm (.728")
Rear: 18.0mm (.710")

Because your pads & rotors do not have significant wear (which causes low fluid) the fluid had to go somewhere. Check under the booster for gooey stuff, but change the master anyway!
Pete

 

Thanks again all for the responses. I checked out the four rubber hoses and all look/feel in quite good condition as do the hoses coming out of the master cylinder. This too looks pretty good and was in fact replaced about 6,500 miles ago but this was in 1994!

Looking at the fluid resevoir again I have to say the fluid itself looks very clean and not rust like at all. It's just oil coloured rather than the blue/green colour of other brake fluid I have used. Is it not possible there is some brand out there this colour?

Thanks.

 

Lots of brake fluid out there in the market that is neutral in colour, but nthyen turns brownish with heat. Speaking of which I doubt that any brake fluid remains "colored" very long after it begins to be exposed to the level of heating brake fluids are designed to endure.

I just installed new brake pads all around on my 1992 LS400 this past weekend and as a result the fluid level came back up to "full".