Drove about 300 miles west (and back later that day) this past weekend, and on the way back, the (what sounds like rear) brakes started making some weird noises.

We had come from just east of Grand Junction, CO, so we'd been going up and down some pretty steep hills for a couple of hours. As we were descending into Denver, whenever I would apply the brakes with firm pressure, there would be this sort of whiney, mechanical groan. The truck would slow down, but it made that horrible noise. As we got off the highway and approached a stoplight, my brakes squealed pretty loudly, followed by a sort of grinding noise.

I checked the brake fluid and it was pretty low, so I went to Napa and got some Dot 3 and filled it up.

I drove about 20 miles roundtrip in stop and go traffic going to/from school, and the problem seems to have cleared up. The brakes are still fairly squeal-ish, but they were beforehand.

Should I get the brakes checked out by a professional, or are those noises fairly typical of a vehicle that has run low on brake fluid? I had the truck at Ford a few weekends ago, and according to them my brake pad depth is okay.

Truck has 60k miles on it.

 

Sounds like your brakes are about gone. Pull the wheel and see if the rotors are "ate" up pretty bad. A deep groan sounds like your pads are completely gone and are grinding into the rotors. Brake jobs on F150's are as simple as can be. The low fluid also makes me believe that the pads are completely gone or almost gone.