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About Brake Fluid

DOT 3 is what Nissan recommends. It's the normal stuff available in the US.

DOT 4 is chemically compatible with DOT 3, but with a slightly higher boiling point.

DOT 5 is silicone based fluid*. NOT compatible with DOT 3 or DOT 4.

More info about DOT 5 fluid:

There are certain mods that are really "trick", but require so much work or cost so much that almost no one will do what it takes to exploit it properly. DOT 5 fluid is one of them.

  1. DOT 5 fluid is silicone based*, rather than glycol based like DOT 3 & 4. Being silicone based, DOT 5 fluid won't absorb moisture, while DOT 3 & 4 does. What this means is that you have to completely clean out your brake system of any traces of the previous fluid as well as any moisture, otherwise you risk causing corrosion in the system. Brakes will continue to absorb moisture near all seals anyways, so you will need to bleed the brakes on a regular basis to remove the moisture.
  2. Since it carries a DOT rating, it must be compatible with the other DOT brake fluids. Note that I said compatible, because it certainly doesn't mix with the other fluids. Another reason to flush the system completely of the old brake fluid.
  3. DOT 5 fluid tends to be rather viscous. When adding it into the system, it's real easy to get air bubbles in it which don't want to come out. It's impossible to get your brakes bled properly if there is air entrained in the brake fluid. And additional viscosity may not work with ABS.
  4. If you're getting the stock or B13 brakes to a temperature where you need a DOT 5 fluid, you're going to be seeing other failures in the braking system, like the rotors warping and cracking, pads burning up, and the pin boots melting (if you're lucky) or catching on fire.

And for some more information, check out:

* There are actually two types of DOT 5 fluids. There is a SBBF (Silicone Based Brake Fluid) and an NSBF, or Non Silicone Based Fluid. DOT 5 NSBF's are not widely found, however, and are beginning to get more recognition as their popularity grows.