# Brake Fluid discussion **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [September 26, 2014, 9:19pm UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374 "2014-09-26T21:19:21Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![BigSam](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@BigSam](https://community.cartalk.com/u/BigSam)\ **Post date:** [September 26, 2014, 9:19pm UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/1 "2014-09-26T21:19:21Z")
I recently had a mechanic replace the brakes on our Toyota Venza. I asked if they were going to replace the brake fluid - mechanic said no, just top it off. In the past when I did a brake job, I always drained the brake fluid and replaced it. I thought this helped preserver the brake lines, master cylinder, etc. Is there something new with brake systems now; was I wrong with my past practices? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [September 26, 2014, 9:31pm UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/2 "2014-09-26T21:31:44Z")
Yes, brake systems have changed. They contain different metals that react to one another when old, damp brake fluid is in the system! I commend your practice of replacing brake fluid. Find a new mechanic or insist he change the fluid. It prevents corrosion in your brake system and raises the fluid boiling point considerably. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [September 26, 2014, 10:15pm UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/3 "2014-09-26T22:15:42Z")
Did they at least test the brake fluid for copper content. > **[Phoenix Systems Brake Fluid Test Strips (100 / Tube) PHOFASCAR-1-100: Advance...](https://shop.advanceautoparts.com/p/phoenix-systems-brake-fluid-test-strips-100-tube-phofascar-1-100/22981645-P)** > > Save on Phoenix Systems Brake Fluid Test Strips (100 / Tube) PHOFASCAR-1-100 at Advance Auto Parts. Buy online, pick up in-store in 30 minutes. These test strips detect the amount of copper dissolved in the brake fluid to indicate when the brake fluid should be changed. Tester ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [September 26, 2014, 11:15pm UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/4 "2014-09-26T23:15:16Z")
Do those test strips detect moisture in the fluid? Particulate debris gathered in the calipers? Whenever I’ve changed the fluid in a car that hasn’t had it in a long time there’s nasty looking muck that comes out when I first open the bleeders. Always seems to look worse than what was in the reservoir. I change the fluid on my non-ABS car every 3 years. With ABS I’d do it every 2 years. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [September 27, 2014, 4:29am UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/5 "2014-09-27T04:29:35Z")
I usually replace the brake fluid in the portion of the brake system I’ve been working on. I have to bleed it anyway, so replacing it isn’t that much more difficult. I guess a person could argue the less you do, the less chance you’ll get contamination into the fluid. There’s some merit to that argument I think. I don’t replace the brake fluid for no reason for example. Only if I’ve done some work on the system so I had to open the hydraulic lines anyway. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [September 27, 2014, 4:37am UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/6 "2014-09-27T04:37:44Z")
If there’s dissolved copper in the brake fluid, it means there’s enough moisture in the brake fluid to cause the copper to oxidize. Tester ---
**Author:** ![wesw](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wesw/32/2713_2.png) [@wesw](https://community.cartalk.com/u/wesw)\ **Post date:** [September 27, 2014, 4:38am UTC](https://community.cartalk.com/t/brake-fluid-discussion/87374/7 "2014-09-27T04:38:47Z")
whenever I change pads or shoes I flush all my lines the old brake fluid is always very dirty, dis-colored, when I do.