Im a newbie at boats, This is my second boat, my first boat had a 55 evenrude, but this was 20 years back, my new boat is a Kencraft Chalenger center console. I just want anyone to give me some advise as maintenance, before I bought the boat I was there when they did the compression check and eveything was normal,so it passed. Mainly I want to know What type oil to use?? I have put a gallon of Super Tech TC-W3 certified but I have not run the boat yet with it, I just topped of the reservoir.Should I change the spark plugs or not?? and one last thing, Is the prop that I have any good, the prop is a 17 pitch stainless steel, mercury marine Vengance.