I have a 97 Honda Civic EX coupe.

Should I go by certain mileage as in every 50K miles or whatever? Or should I physically go look at the pads? If so, how thin is too thin? But I remember couple times the mechanic took the pads out it still look pretty thick to me (~.25" if I remembered right) it definitely had some to go until it hits the base material. So how do I tell when I should change my Brake Pads?

Also, if i do change anyone of them I should change all 4 right?

Thanks!
Would waiting until the squeeler make sound damage anything?

You can't go by mileage because every driver is different and many people have more stop and go driving which wears the pads faster.
Best way is to look at pads during tire rotation. With the wheels off the pads can be easily checked for uneven wear to determine if they need replacing. That is how I caught an early problem and prevented damage to a rotor. One side had worn much faster than the other due to a slight flaw in the pad.

Some pads have a device that make a high pitched squeal when they are getting close to needing replacement. If you wait till you hear metal grinding on metal you have waited too long and will most likely need to replace the rotors as well. Big expense!!

If you don't rotate your own tires every 6000 miles ask the shop people who do it for you to check it at tire rotation. That will give you piece of mind and save you a lot of money.
Usually the front will wear out first so you need only change BOTH front ones at the same time.

Always change the pads on left and right of the same axle, front or rear. ON a car I drove for 180,000 miles I changed the front pads almost twice as many times as the rear….

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