KC98LS

Hi all,



My brake fluid is a bit old, was going to replace it. As I understand it Toyota calls for Dot 3.


Am I correct that Dot 4 can be used in place of Dot 3 as it is superior? Will I need to flush the lines, or is mixing 3 with 4 an OK practice?

What fluid have you used?



Thanks.

96UCF20

You will be fine with using DOT 4 brake fluid instead of DOT 3. I would recommend flushing your brake system for best results. Personally, I'm using ATE TYP200 DOT 4 brake fluid in my 1996 Lexus LS400 and I am very content with the performance.

aptoslexus

Flush out all of the old fluid.

CELSI0R

DOT 4 can be used in place of DOT 3, but I would keep using DOT 3 instead.

The benefit of DOT 4 is that it commonly has a higher boiling point than DOT 3, but this comes at a cost. DOT 4 brake fluid is more hygroscopic. This means that DOT 4 brake fluid will break down faster, which will cause its boiling point to go down sooner, in comparison to DOT 3.

Since DOT 3 is less hygroscopic, it will break down slower than DOT 4, and maintain its specified boiling point longer.

Long story short, you may need to change your brake fluid more often if you use DOT 4, because DOT 4 has a higher rate of moisture absorption.

Also, consider the fact that DOT 3 and DOT 4 fluids have different chemical compositions. When the LS 400 was made, it was designed to use DOT 3 fluids.

Here is one source to cite from an automotive forum that I looked at. Also, here is a more in-depth read from StopTech.com

GasBuggy

Use DOT3 fluid. You're not going to be doing any driving that benefits from DOT4

AandSC

I used DOT 3 when I did my recent brake service. It's what the car came with and no reason not to continue using it.