Brake fluid loves water. By this I mean that once you crack a bottle open don’t leave it open. Don’t leave the lid off the MC either. Brake fluid will pull the water vapor out of the air like a fat kid on cake. Water will boil at 212 deg and brake fluid can take more than that so if the fluid in the brake lines on your car have water in them it’s in the calipers and/or cylinders and will boil creating vapor which then compresses and you get spongy brakes.
I’m down to save a buck but not on brakes so if you have an old bottle of brake fluid toss it.
For a street driven car DOT 3 is fine and check it ant least once a year for color and level. I typically flush mine every 3-4 years depending on miles.
If you road race move up to some good DOT 4 at a minimum. I regularly helped my buddy flush the brake fluid on an SCCA AI car. After four 20 minute sessions it was impressive how my buddy stopped as it was black as night. He was using Motul and it is not cheap and literally everyone in the pits was using it even the Miata guys (I’ll leave that one alone).
+1 for the Motove bleeders as they are the schniznit. Would not bleed the ABS on my Coupe without it. They make brake bleeding so much easier and it’s a one person show.
I run Valvoline brake fluid and they have a really good knowledge base here:
Brake fluid selection is a particularly important task of vehicle maintenance. Different types of brake fluids match the requirements of specific braking systems. The most common ones used today are DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluids. Are all brake fluids the same? If not, what is the...