emo236

Does the sound stay there? Or does it go away after like 5 minutes or less? If that's the case, it's your timing belt tensioner. It's more of an annoyance than anything. Replace it next time you do your 60K. If it stays, then it's belt. It could be your timing belt, accesory belt, etc. It's probably loose or the pulleys aren't very well oiled. Oh, and I suppose your somewhat new to this, but this is the 350z section, you'll get more of the help you need if you post in the z32 (300zx) section right beneath this one. Hope that helped...feel free to ask for any questions.

91zxtt

Try tightening your accessory belts (ac, ps, wp). That is more likely than your timing belt squealing. You could also try spraying a cleaning solution (simple green, etc.) on the accessory pulleys while the car is running. It will clean any oil or grease off of the pulleys; which could cause the belts to squeal also. I don't think having your car in gear or out of gear should make a difference. It's probably just a coincidence.

Riz Z Speed

There's actually a belt dressing that is sold in most auto parts stores for that instead of using something like simple green. Most cleaning solutions like that will end up drying out the belt further, promoting cracking and eventually breakage.