I know my car needs a tune up - but just recently I've noticed a high pitch whining noise (almost like a whistle) coming from the engine when I accelerate. It can clearly be heard from inside the car so it makes me think maybe it's under the dashboard?

My car is a V6 2002 Chev. Impala 4-dr. Sedan. I am going to get transmission fluid tonight after work and I just added 2 quarts oil in case that had anything to do with it.

the noise doesn't get any louder when I hit the gas but stays this constant "whistling" pitch