Yeah, if the squealing stops when you oil it, my concern is the little pinched off tube on the front plate is clogged. That can easily happen. But I hate to be the bearer of bad news because unless someone knows of a trick that I do not, I don't think you can even see it without removing the cover.
If you do remove the cover, it might be a good time to do the tech tip mod that allows you to take the cover off without dropping the oil pan. Start with checking the seal for abnormal wear in one location first. It was his 'squirting oil on it making it stop' comment that has me wondering about oil circulation.
