whistling noise at low speed and middle of the day usually

When you start it up and it whistles, remove the oil cap or pull up on oil dipstick if it has one. If the whistle goes away and there is a lot of vacuum from the crankcase then the oil separator has failed. The intake manifold will need to be removed to access the part and I would recommend you replace all the PCV hoses as well since they will break when removing the intake. Usually with an internal vacuum like that the Check Engine light or Service Engine Soon light should come on with fuel trim faults. I have also seen it where it is so bad that smoke will start to come out the tail pipe from it sucking oil. Let us know how that first test turns out.

I tried removing the dipstick while the engine was running and the whistling was present. No luck. Whistling continued.

Okay then, if the noise is more of a chirping sound then spray some WD40 on the belts. If noise goes away replace the belts. If it still makes noise, have your mechanic remove the belt and run the engine again. If the noise goes away then spin each pulley one at a time and check them for play. If the noise is still present when the belts are removed then your mechanic is going to need to try to figure out what is going on. Those are simple tests you can do before throwing parts and money and still end up having the same noise? Let us know how it goes and what you end up finding.

Car is back to new after replacing belts and pulleys. Thank goodness. Thanks for your input!

Glad you could get it fixed please use 2CarPros.com anytime we are here to help

Best, Ken