I topped up my engine coolant on my BMW E90 then afterwards there is a screeching/squeaking noise when I start the car and also when I'm driving, worrying about what it could be?
My car has 193000 miles.
My car has a manual transmission.
If your cooling system is getting low on coolant then you may have a leak that is getting on the drive belts and causing the noise. You should have the cooling system tested for leaks as soon as possible to prevent a breakdown and possible engine damage. (Check cooling system.)[https://www.yourmechanic.com/services/car-is-overheating-inspection]