Scotty, et al,
2007 Lexus ES350 156K miles
Just got my transmission serviced this morning at my local Toyota dealer and they gave me a sheet of recommended additional service via their complimentary multi-point inspection.
One line item doesn't make sense: "Brake Flush: 2% Moisture Content"
The service advisor said moisture content should be 3%. When did we want any moisture in our brakes?
What he's saying is 3% is the maximum tolerable moisture content. When it gets near that point brake fluid should be flushed.
OK, that makes more sense. The way she phrased it led me to think 2% is not enough. Thank you for your answer.
Moisture lowers the boiling point of the brake fluid and promotes corrosion in brake components. Typical rule of thumb is to flush and replace every 3 years.
boiling points:
Federal Motor Vehicle Safety Standards:
https://www.law.cornell.edu/cfr/text/49/571.116
Also keep in mind that unless they used a refractometer, those brake fluid testers are super inaccurate. Just make sure your fluid is clean and clear, and follow the recommendations in your owner's manual.
Thanks for your input.