cx876

or just get an electronic brake fluid tester from Amazon for $14,
it's able to measures moisture from 0%-4% so you know exactly when to change your fluid.

Sunnyslope48

GREAT IDEA. Where you drive makes a lot impact on the amount of moisture that might be absorbed by the brake fluid. If you live in the humid South vs say Arizona desert where humidity is commonly 15%, you're going to need to change fluid much more often in the humid South. Also, the type of brake fluid influences the water absorption. DOT 3 doesn't absorb as much moisture as DOT 4. So testing to see what moisture level ACTUALLY IS, that's the best thing to do. Then there's no guessing - you KNOW.