how often do i need a “brake flush?”
Most people say every 3 years or 36000 miles . Why do you ask ?
How often does your owner’s manual say to do it?
Owners manuals are better for mandatory maintenance and often fall short when it comes to other preventative maintenance such as brake fluid and transmission fluid changes.
Anecdotal evidence, Had it done every time with a brake job, sure I only needed brakes done at 75k miles and 160k, but 17 years old, 198k miles got rear ended and too expensive to fix cel to get relicensed, but never a brake line problem. Not saying it is right, just speaking for myself. Live in the rust belt!
I do it every 3 years.
IIRC it was my 1981 Accord that called for it in the service schedule.
Done it ever since the next 30+ years, even though it’s no longer in the factory schedule.
The old fluid comes out looking like apple juice, new fluid goes in water clear.
When I used to buy older used cars brake flush was something I’d do right away; and the fluid sometimes looked pretty funky.