Wow! You've really gotten a ton of miles out of your pads so far! I just checked with a flashlight and the groove you mentioned is definitely not there anymore, so I will definitely need to replace the pads this week. There is a "score" on the driver side rotor -- does this mean I should machine the rotors or just replace the pads?

Also I have been getting occasional squeeking -- is this from the score or something else?

 

Neither. Measure the rotors. If they are still thick enough to have ground, then have a machine shop Blanchard grind them flat again and measure again. If they are still thick enough after grinding, then run them with new pads. If they are not, replace them. The machine shop should be able to tell you if they can be resurfaced or not. Just avoid a brake lathe, they leave a very coarse surface that will really shorten the service life of your new pads. Blanchard grinders are also called centerless grinders and it's what the factory used to put the initial finish on your rotors.

 

I'm not sure I understand, as this is my first time changing brakes on this car. What do you mean by 'ground'? I ordered new pads and shims from Sewell Lexus, which will arrive on Thursday. My plan is to simply replace the pads and not machine the rotors at all. I have never had any vibration, fade, or any poor braking performance, and the rotors only have 15,000 miles on them.

When I use the clamp to expand the caliper for the new pads, am I supposed to open the brake fluid reservoir (and is that what is meant when people say to release the pressure in the master cylinder)?

 

I wouldn't open it, but I'd put some thick rags underneath and around it in case it spills. You don't want brake fluid on your paint.

Replacing the pads without measuring the discs is not wise. It is unlikely the discs are worn below limits, but without measuring them, you are taking a big chance.

What I mean by ground is resurfaced with a centerless grinder, NOT a brake lathe.

 

So the metal rotors themselves actually wear down and get thinner and thinner over time with braking?

 

Yes. It's unavoidable.