I have a 2002 yamaha 115 hp 4 stroke engine, I have drained the old oil and installed the new filter but have just noticed the oil im replacing with is syn. 4 cycle 25 w 40 engine oil. The old oil was 10 w 30 4 stroke oil. I have used syn. oil in my cars and have very good luck with it and like it. I was wondering if there are any problems with this change? Thanks Dave