For one thing, if it's 10 to 15 years old, you might want to get a new sax, BUT heres some suggestions.... For one, try looking at the palm keys, if they aren't coming down all the way, that can cause a lot of squeaking. This has happened to a lot of old saxophones I've dealed with. You could also try checking if theres any holes in any of the pads, or pieces of the pad that are abnormally sticking out/in.

How long have you been playing? Check posture, make sure your neck strap is adjusted so that you can play with your back straight.

Oh, you can try getting a new ligature, I prefer the Bay brand, it helped me with my low notes. Also, if you've recently run your mouthpiece under hot water, that would most likely be the reason for your squeaky notes. If you did, I'd recommend getting another MP.

dont listen to these idiots who suggest its the mouthpeice or the lig, use more air, see if pressing the key with more force helps