What Brake Fluid Should & Should Definitely Not Look Like

About a week ago I bleed my brakes on my car, a '96 Honda Accord.  On the right is the old, dirty, and pretty nasty brake fluid I had in my car.  On left is brand new clear, clean, and new brake fluid, which is how all brake fluid should look.  The difference in color is very clear.

New Brake Fluid... Old Brake Fluid

The brake fluid I had in my car was obviously dirty, old, and black.  Did you know old brake fluid is a safety issue?  The reason is DOT 3 and DOT 4 brake fluid is hygroscopic, meaning it absorbs moisture.  Think of brake fluid like a sponge.  Overtime the fluid naturally absorbs moisture, which is why it must be changed.  Moisture exceeding 2% is considered excessive, and brand new brake fluid has about 1.5%-1.65% moisture.  Brake fluid is designed to have a high boiling point due to immense heat generated when braking.  Moisture causes the normal brake fluid boiling point to drop, which can lead to brake fade or failure in extreme cases.

Contaminated brake fluid can also potentially affect the performance of your brakes and damage parts.  All that dirt and moisture was moving through the brake lines, calipers, and wheel cylinders.  When the dirty brake fluid was going through the ABS Actuator, delicate solenoids and motors can behave unpredictably.  (My brakes work much better now that I flushed my brake system.)

It is easy to tell when your brake fluid is dirty, but how can you tell when you brake fluid has moisture?   There are specialized strips to test the moisture content in your brake fluid, but no shop I have seen uses them.  They will usually see people with brake fluid pictured on the right, and just recommend a brake flush.  You could buy these strips in an auto parts store if you are curios to know.

Most manufacturers recommending flushing your system of old brake fluid and replacing it every 30,000 miles or 2 years.  I think this is a good rule of thumb and should keep your vehicles brakes working well.

I thought this would serve as a good lesson.  Hopefully you will change your brake fluid and not let it get this dirty!

The following two tabs change content below.
Adam loves cars and anything with wheels. He has many interests and passions but he especially loves writing and blogging. Hence starting this auto blog.

Published by


Adam loves cars and anything with wheels. He has many interests and passions but he especially loves writing and blogging. Hence starting this auto blog.

9 thoughts on “What Brake Fluid Should & Should Definitely Not Look Like”

  1. Hey adam, just did a quick search to verify if my brake fluid is in good/bad shape and took a look at your blog entry here, very useful thanks. The fluid in my Toyota 05 corrolla looks like the new stuff on the left, even though it’s years old, but I will change/flush it anyway.

    1. Glad you found my post helpful Antony.

      Even if the brake fluid looks ok in your Toyota Corolla from looking at it through the brake fluid reservoir, honestly it sometimes is still dirty. Did you take the cap off the reservoir and inspect it? Also the brake fluid in the lines can be dirty and accumulate moisture over time. The brake fluid in the lines tends to be pretty dirty fluid when I’ve done brake flushes. That’s why it’s recommended you change your vehicles’ brake fluid every 2 years, or course every year is more ideal. The older the fluid is the less stopping power it provides.

      So if the brake fluid in your Toyota Corolla is a few years old you should definitely flush it even if it looks ok. Have you ever done a brake flush before? It’s pretty simple and there are a ton of great DIY articles and videos on how to do it properly. I should probably record one myself.

      This reminds me that I probably should change my own brake fluid on my Honda Accord. 🙂

      1. Hey Adam,
        so it was an Amber colour and I know for a fact it is pretty old, Toyota placed a fine mesh insert/screen in the master cylinder reservoir to stop any crud from finding its way into the system, gotta love some of their design decisions. I replaced/bled 800ml and the new fluid is translucent its also synthetic I believe you can’t buy the organic (non-synthetic) anymore. Went great till I managed to crack off one of the rear bleed nipples so i’ll have to fix that by changing out its cylinder or drilling out what’s left of the nipple (good thing I bought those cobalt drill bits a few months back).
        I haven’t heard of a break flush but will look it up on YouTube tonight, I did have a gunsons brake bleeding kit but it would play well with the reservoir so had to bleed the brakes the old fashioned way, anyway wish me luck with fixing the busted brake nipple! Oh and I just bought a new jack too… Not the same as yours but it performed admirably today.

        Cheers Antony

        1. The Japanese know how to build cars. The Germans do too, just they use software trickery to cheat emissions apparently. 🙂

          I haven’t seen “regular brake fluid” in awhile at any local auto parts stores. Definitely seems like most places only sell synthetic brake fluid nowadays, which is good in my opinion. Synthetic is much more effective, better for your brake system, longer lasting, and doesn’t absorb as much moisture. I hate when parts break when you are working on your car. That’s part of auto repair though, hope you get the bleeder nipple fixed soon.

          I use the hand operated bleeders where you just open up the bleeder valve and suck out the fluid. This is more effective and is requires much less time and effort. It was the way I did it when I worked in a shop and customers never complained about mushy brakes after a flush. Old timers seemed to like the old method of one person in the car depressing the brake pedal while the other person opens the bleeder, but I never liked that way. Always felt like too much hassle. These hand operated ones are nice but too tend to wear our easily if you use them a lot. For a DIY auto mechanic they are great. I’ve seen brake bleeding machines that actually hook up to all for brake calipers and the reservoir and suck out all the fluid. They are pretty cool but mainly dealerships have these for luxury cars as they are the only places that can afford that type of equipment.

          Whatever type of brake flushing system you use I found it’s best to suck out the dirty fluid in the brake fluid reservoir first, this lessens the chance of pulling dirty fluid through the car’s entire brake system. Make sure to not let it get to low and add new brake fluid to the reservoir.

          Are you referring to this Arcan Floor Jack?


          It’s really had to beat that floor jack for the price. I’d highly recommend it even if you have another jack Antony. What jack are you using now?

          1. It’s a 3 ton big red torin floor jack, weighs about 90lbs, it was on sale about the same price as yours, no doubt there are better ones out there but it seems to be made out of good materials and is put together well, I’m just glad I have it as I couldn’t do much work on the car without it.
            Whilst cleaning and rust proofing yesterday I inspected the suspension and bushings, I found the lower ball joints boot is split so il have to replace that at some point, it doesn’t appear to be affecting the car yet.
            Looked up the procedure on replacing the rear brake cylinder, seems straight forward though il have to buy a quality flare nut wrench to release the hard brake line, this is plan “B” if I can’t solve the broken nipple problem by extraction.
            I know the hand powered tool you are talking about, I wouldn’t mind one of those, nearly a hundred dollars here in Canada though for a decent quality one, I wonder if it could be done with a large syringe?

          2. If the boot is split that means that grease is out of the ball joint and dirt, mud, and crud can get in there. The ball joint will separate at some point if you leave it like that which is going to cause a lot more damage to your suspension system and car in repairs then if you just replaced it. You should replace both ball joints IMMEDIATELY if possible.

            Replacing a brake cylinder (aka caliper piston), while possible, is kind of a hassle. You can get it set in wrong in the cylinder bore housing so it won’t push out straight. Also I don’t know of many auto parts stores that stock brake parts like caliper pistons but you I’m sure you can definitely buy them online in Canada.

            EDIT – Oh do you actually mean the wheel cylinder on your rear brakes?

            It sounds like you just need a new bleeder nipple though, right Antony? Or are you looking to replace the entire caliper? Yeah, there is not much to it and replacing the entire caliper might be easier than drilling that out. You might save more time and hassle by just replacing that the caliper. You do need flare nut wrenches to get caliper off the brake line and you just swap in and install the new caliper. Actually most likely you will buy a remanufactured one. For your Toyota Corolla buying a complete caliper is not that expensive but just make sure you get the correct brake caliper for your trim and model.

            Wow… $100 dollars for a hand operated bleeder pump in Canada? Here in the United States they sell for about $30-$40. Of course maybe if I bought a $100 it wouldn’t break so easily, I’ve never seen one anywhere for $100 in the US. 🙂

  2. Lol yes wheel cylinder, apparently it’s held on with only 7ft lbs of torque… I agree it will probably be simpler replacing the cylinder.
    Yes the philosophy here is “sell a little for a lot”

  3. Bambi Flowers says:

    Help! I accidentally put 1-2 oz of windshield washer blue fluid in Brake rese voir. Realized my mistake and used a cotton cloth to wick it out of top of reservoir . Fluid showing is brown. Have not driven car yet since this . What should I do now!

    1. First get the fluid out of the brake reservoir then you should completely flush the the brake system. I’d use a lot of brake fluid since washer fluid is a water based solution. Water isn’t good for your braking system Bambi Flowers. It reduces the effectiveness of the brake fluid for braking.

      Do you think you can handle flushing the system? It is an easy procedure and there are lots of Youtube videos on how to do it. I recommend getting one of those MityVac pressure guns to pull the fluid out from each brake line.

      If you are not comfortable with doing this it likely could make it to a repair shop without too much trouble. I’m not recommending you do this though.

Leave a Cool Reply