Ask the Expert: Should my customers be concerned about having moisture in their brake fluid?

Feb. 10, 2016
High levels of moisture can cause brake fluid to boil under extreme operating conditions.

Q: Should my customers be concerned about having moisture in their brake fluid?

True or False:

No. 1: Brake fluid is hygroscopic. 

True: Brake fluid absorbs water. Vehicles in humid areas like Florida will often have over 3 percent moisture, while vehicles in Nevada are capable of staying below 2 percent.

No. 2: High levels of moisture can cause brake fluid to boil under extreme operating conditions.

True: With the help of a few national chain service providers, we tested the boiling point of over 469 vehicles across the US. Of those 469 vehicles only six had a boiling point lower than the DOT standard. In theory, brake fluid could boil, but it is very unlikely.

No. 3: Moisture in brake fluid causes corrosion.

False: Consider that antifreeze and brake fluid are both derived from glycol. The addition of 50 percent water to antifreeze actually helps protect a cooling system from corrosion. Two percent or 3 percent moisture in brake fluid also helps protect a brake system from corrosion. Oxygen is the oxidizer that begins the corrosion process inside a brake system. One out of two vehicles on the road have corrosive brake fluid that will not pass the DOT corrosion test.

Information provided by: Phoenix Systems LLC

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