Since the '08 Heritage has an oil tank and oil runs through oil lines, oil pump, etc. into the engine, how does one really get all the old dirty oil out of the engine during an oil change? I have read elsewhere there is additional 1/2 qt. of oil within the engine and oil lines that should/could be removed during an oil change. How do you get out all the oil within the engine? Is there another drain plug located on the engine that will help drain the remaining oil? Any help on getting out all the oil is appreciated.