Dot 3, Dot 4

[Patrick]

Hi.

On my car's brake fluid reservoir cap, it states "Use DOT 3 or DOT 4 fluid only". So, which do you think is more recommended for my car? Is it DOT 4, as it has a higher dry and wet boiling point?

Apart from that, what are the colors of DOT 3 fluid and DOT 4 fluid? I read that it is not recommended for us to mix DOT 3 and DOT 4 fluids right? If so, what are the colors of DOT 3 and DOT 4 fluids, so as to allow me to add the same type of fluid?

Besides that, I always read that we must fill the reservoir with brake fluids from a sealed-container. If the brake fluid level drops a bit (but not too much, and not enough for me to fill in an entire bottle of brake fluid), what should I do? Leave it alone? Or fill it until full, then dispose the remaining fluid?

Thanks!

[ecstasyracer]

I would also like to know about this too. I asked some mechanic today about putting in dot 5.1 fluid and he siad that it was a bad idea and I can only use dot 3. Why would it matter since the boiling point is just higher?

[hjr]

mainly the only differency is the heat caqpacities. Dot 4 can get hotter than dot 3, and so on. Also, i think that a car with ABS needs dot 3 to 4 for some reason.

[DSM Power]

Generally 3 and 4 are interchangeable. You want to avoid Dot 5 which is a silicone-based fluid and not that great for the seals... I've heard that 5.1 is non-silicone but I have no experience with it.

As for the color, my last batch was clear out of the bottle. The color doesn't mean anything, other than it's probably time for you to change the fluid! :tongue: