I just replaced the brake lines/rotors/pads on my car and am trying to bleed the system. I just noticed I've been adding DOT 5 to a stock DOT 3 filled system...

I was wondering if I'd be okay if I continue to flush until the system is full of just DOT 5 or if that fluid shouldn't be used at all in the car?

 

Great, searching gets nothing useful but start a thread and magically the links at the page bottom tell you everything you need to know...

 

kinda f'd up how that works huh?

 

Just don't use Dot 5 it has silicone in it and will fubar your ABS, 5.1 is glycol based and safe (If I am getting this right)

Dot3/4/5 are just temp specifications. If you completely flush you system what is there to thing about?

If you want a real easy time of the job I recommend using something like a Motive Power Bleeder it has worked great for me and worked much better than any vacuum based system I have tried before.

 

Thanks, I'm trying to use a vacuum system right now and it does indeed suck...good thing though, it should be easier to get all the DOT 5 out since it didn't get a chance to leave the master cylinder yet...

 

it is okay to use any dot brake fluid specified or higher. example : dot 3 system, you can use 3, 4, 5 etc.

But you cannot use any dot brake fluid lowered than the specified dot system. example: dot 5 system; you cannot use 3, 4, and etc.

Hope this helps.

-AzeKnightz

 

DOT5 fluids are silicone based so they are not directly compatible with DOT3, 4 or 5.1 fluids. For the most part, DOT3, 4 and 5.1 fluids are compatible but brands do vary in that regard.

It's not a problem to move up to DOT5, but since it's silicone based it's not easily flushed out to go back to a polyethylene glycol based fluid.

The main questions for the OP is if he has DOT 5 or DOT 5.1 fluid....

 

You may want completely flush your brake system with some new DOT 4 or 5.1 brake fluid. (5.1 not the same as DOT 5)

Adding something other than DOT 3,4 or DOT 5.1 brake fluid to your Master Cylinder can cause the rubber components to swell, causing your brakes to eventually lock up.

Before all the naysayers chime in, I've seen it happen on my Miata (someone else did it - I got to fix it), the mechanic who looked at the car when the brakes started acting strange has seen it a number of times (he said he's seen it happen when someone is getting divorced), and a friend that is a Toyota mechanic has also seen it happen. (Jiffy lube was the culprit, and they had to pay to replace the brakes)

In my case the brakes just started acting kind of strange, brake pedal pressure was uneven. I had a mechanic I trust check it out, and the brake fluid was like honey.

Eventually the brakes locked up so tight on my Miata that I could barely move it into the garage to fix the brakes. The 'fix' involved replacing everything except the rotors, pads and hard lines.