Some answers to your questions: The squealing noise from your engine may be from the idler pulley bearings. I would thoroughly check this out before getting into the water pump. Try taking the a/c belt off and seeing if the noise stops. What kind of engine oil you use is a matter of personal preference. Remember that synthetic is more slippery and therefore leaks out easier IF you have an oil leak. I have Penzoil 10w-30 in my engine right now. That's a bit thin, but the weather is cold. In hot weather I would use 20w-50. Walt Tampa, FL