The mechanic said he used OEM parts and said he would drain and refill the car with the proper coolant solution. Which is great. I've been doing research on the howling noise and found this thread that points out that I most likely need a new carbon control valve
http://www.renntech.org/forums/topic/6332-howling-from-fuel-vent/
I guess my next question is what i should do with the mechanic. I feel like he should've been able to figure out what my car needed, especially after two tries. I guess what I'm asking is should I demand that he fixes my car without me paying for the carbon control valve. He did promise me the CEL would be off after the first payment i made (1400) . I'm just frustrated because I wanted all of these little payments I'm making to be on one bill and given at the start. Is that a ridiculous demand to make?