I am buying next week from a friend a Yamaha 15 4 stroke that was new 5 years ago -- was run ONCE for an hour 5 years ago (for an hour) and ONLY one other time 2 years ago for 30 minutes( the second time by me) I plan on using a new tank, line and gas. Do I need to worry about changing the oil or the water pump or the lower unit oil or anything else before taking out on the lake?