Oil change wouldnt have anything to do with it. You need to have them inspected. Even if you can see the rotor through the rim, the other side of the rotor may be grinding from worn out pads... or the wear indicators on the pads may be contacting the rotor. If the pads are ok then it's just dust, you can spray them out with water or brake cleaner.

If it only happens when you brake, it's not oil related. Could be worn brake pads, corroded caliper pins, corroded pad slides, scored rotors, uneven pad wear. Improper or missing brake grease. Get it checked out. It's not going to fix itself.

gentle braking polishes the rotors and causes a screeching sound try a few hard stops to get the glaze off the rotors , on an empty road when it's dry

Brake pads usually have a metal tab that scraps on the disk when the lining is getting low. You can continue to use them but you will need to replace them because once the lining is completely gone there will be metal to metal contact which will require extra repair costs. Alternatively there could just be a stone in the brakes that you can flick out with a screwdriver, if you can see it.

Brake pads are worn.

hello,

i got a 2004 ford car. 130 k miles on it

was getting a screeching sound whenever i apply brakes.this has been happening for the last 1 week.

just got the oil changed 3 months bank and still only 2k miles on it.

what could be the reason..it is safe to drive in this condition