I had my rotor carriers and Brembos powder coated black (changed calipers). When I drained my brake fluid into a white cup the oil was very dark and there were droplets of water in the oil. I did not take pictures but you are going to have to take my word on it.

Not Brembos but the Tikico's I took off after 7K Mi.

I have read that brake fluid oil retains moisture and after one year (that I had these calipers on) I can positively tell you that it does.  We are only talking under $5! WTF? For under $5 you could possibly have better brakes and there is no such thing as having too much brake (unless lock up occurs).

Copied & Pasted info:
OT ratings So, what exactly is the DOT rating telling us? More importantly, what is the DOT rating NOT telling us? A quick look at FMVSS116 – the US Government’s Specification for brake fluids – will tell us all we need to know…

DOT 3 fluids are usually glycol ether based, but that is not because they are required to be. In fact, FMVSS116 makes no mention whatsoever about the chemical compounding of brake fluids – it simply dictates the fluid physical properties. However, the brake fluid industry has by consensus decreed that glycol ether fluids are the most economical way to meet the requirements, so there you are.

These glycol ether fluids are typically a by-product of the process used to make certain paints and varnishes. By definition, DOT 3 fluids must have a minimum dry boiling point (measured with 0% water by volume) of 401F and a minimum wet boiling point (measured with 3.7% water by volume) of 284F. That’s really about all the specification says as far as the performance enthusiast is concerned.

DOT 4 fluids are also glycol ether based, but have a measure of borate esters thrown in for improved properties including increased dry and wet boiling points. A seldom talked about characteristic though is that because of this chemistry, the DOT 4 fluid will have a more stable and higher boiling point during the early portion of its life, but ironically once the fluid does actually begin to absorb water its boiling point will typically fall off more rapidly than a typical DOT 3. By FMVSS116 standards, DOT 4 fluids must have a minimum dry boiling point of 446F and a minimum wet boiling point of 311F.

Does this make DOT 4 fluids better than DOT 3 fluids? Not always. Remember, the boiling points listed are minimums and there are DOT 3 fluids out there with higher boiling points than some DOT 4 fluids. The real differentiating factor should be that if you run a DOT 4 fluid you really should change the fluid more often than if you use a DOT 3, if for no other reason than the rapid fall off in boiling point with time.
We won’t even discuss DOT 5 fluids as they are completely unacceptable to the high-performance enthusiast, but we’ll include them in the following table for completeness.

PROPERTY: ********************* DOT 3,***************** - DOT 4,**************** - DOT 5
Dry BP (F)@ 0.0% H2O: ********** 401,******************** - 446,****************** - 509
Wet BP (F)@ 3.7% H2O: **********284,******************** - 311,****************** - 356
Chemical Composition: ****Glycol Ether Based,****** - Glycol Ether /Borate Ester,********* - Silicone Based

I am not telling anyone what to do but I would suggest it.

Done