I have a 1998 Mazda Protege with 160,000 miles on it. 9 out of 10 times when I turn on the engine - it makes a very loud high pitched screeching sound (seems like its coming out of the hood of the car). There are no "check engine" lights on and the car runs fine. The screeching sound lasts about 30 seconds and then poof - it stops. This happens in all kinds of weather (hot, cold). My mechanic couldn't find anything wrong with the car (and of course it never makes the screeching sound when at the mechanic's). The noise does not bother me much - but I think my neighbors now hate me
Is this something serious? or maybe just a loose belt or something? Please advise - keep in mind I know nothing about cars.