Does the oil plug need to be replaced each time I have the oil changed?

No it does not need to be changed each time but there is usually a seal or flat gasket on the plug that should be changed. First of all verify the leak is from the plug by wiping the drain plug and the area around it with a rag or paper towel and look for oil seeping from the plug. If the plug is leaking, check its tightness, and if it is snug the leak is caused by a bad or missing seal and/or worn or damaged threads. Over time it is possible - due to repeated removal and installation of the plug that the threads wear out. Sometimes they can be repaired, sometimes the oil pan will need to be replaced. Good Luck! Robert Grove, ASE Certified World Class Mobile Mechanic www.orangecountymobileautorepair.com www.wego2umobilemechanic.com