Just bought my first boat and it came with a 9.5 evinrude totally new to this I'm draining oil in lower end because I don't know when it was done last anyways thr oil was milky when drained. Besides the fact of water being in the oil what does this mean? I have seen a few videos on changing thr oil and they always mentioned a o-ring around the drain and vent screws.... Neither of mine had mentioned o ring???