Hello, I wanted to know when should I change my rotors? I have 20k on the car and the brakes are due for a change since they are squealing badly but my change my pads message has not shown up yet which is strange.

But my serious question is:

My rotors look fine, they have a tiny lip around the edges but idk if I should replace the rotors or keep them for another 10k miles. Can someone advise?

I have the regular brake system with the silver calipers.

Squealing isn't really indicative of anything. A lot of people's cars have brakes that squeal when brand new. I'm guessing with the COVID situation, you're driving a lot less. Which gives time for the rotors to rust up a bit, causing squealing. I noticed the same thing with mine when I took my car out the other day. I replaced my rears at about 25k and the rotors looked like they could go another 25k. I haven't touched the fronts, and am at 30k. But some of it depends on how hard you drive, track days, etc. Best thing to do is pop a wheel off and measure them.

I know my brake pads are due for a change, they are almost gone the tech at the dealer measured them I forgot what it was but they were due for a change, and that was 2k miles ago. The rear pads are a lot worse, and the it's a pretty loud screeching noise, I've been driving around a lot the past few days. Should've my sensors trigger if my pads need to be changed or is something wrong with mine?

Yes, if your pads are worndown the wear sensor should indicate it and you get a message on the dash.

I just ended up changing it all, ordered the parts from my local MB dealer for 1k.

The reason you could be experiencing pad squeal without the indicator light coming on is due to the fact that the indicator is only on one side and that pad may not be quite as worn as the other. I know that sounds weird but happened to me that way.

No that makes total sense, I did hear the loud squealing on the right side only.

Glad I could help but sounds like you are already replacing them

I ended up replacing it all including rotors, BTW are there 4 brake sensors or 2?

there are only 2 brake sensors

True! One on each side (front & back)...I don't remember which side???

passenger side, front and back

I just have my rear brakes replaced at MB Dealership. On my invoice it stated besides the parts: Include application of " Brake Quite" solution, with lifetime " no squeal" protection. Didn't know what brand they used.

I changed the front and rear brakes with Porterfields along with sensors on my 17 Coupe at about 13k miles and just resurfaced the rotors since they didn't look too bad. I'm at about 26K miles now and they still looked ok but will probably change them next time the brakes are due. Hope this helps bro

This has been my experience on prior AMG's, and seems to be shaping up that way for my current one.

Dealerships are very "conservative" with rotor replacement estimates, since rotors have no built in sensors (and there is no money in telling you that replacement is not needed yet). A tech will measure your current rotor thicknesses (with a micrometer) and freely tell you these and what the manufacturer's minimum safe thickness specifications are for rotor replacement. But they will look at you strange and get all awkward if you ask them what the original thickness is.

With the all the numbers you can roughly calculate for yourself how many miles to expect before replacement. For instance, using totally hypothetical numbers to convey the concept, with a 15 mm original thickness, 13 mm current thickness, and 12 mm safe thicknesses it follows that you have used roughly 2/3 of the usable rotor life. If you have driven 20,000 miles since the rotor was new, it further follows that you can probably go another 10,000 miles. Of course, rotor wear may not be exactly linear and you would be smart to change a bit early, say, at 28,000 miles (but keep in mind that the manufacturer's minimum is likely conservative by at least 10%).

Do not expect many techs at 20,000 miles in the above scenario to say you can go at least another 8,000 miles. I have never had one at a dealership tell me this. For example, at 22,000 miles my regular dealer told me my SLK55 needed new rotors soon. I declined. Then I had a cooling related issue in another city at 26,000 miles and went to a MBZ certified shop (non dealer) and while the car was on the lift asked the tech "what do my brakes look like?" He mic'ed my rotors and told me I had "lots of wear left, at least 5,000 miles." At 28,000 miles I replaced the tires at a shop that did brake service as well, and I asked the same question and was told "ask us again in 5,000 miles." At 35,000 I replaced the rotors. [Keep in mind that was me in a light SLK55; My wife used to 'burn' thru a set of rotors every 20,000 miles in a heavy E420.]

This is the lube that Mercedes uses to reduce brake squealing

Thanks. Others who use OEM brakeparts may want to know.