Mercruiser 7.4 MPI oil leaking

[Silvertip]

Found the oil pan plug and its all good. I was told from a dock neighbor that switching to synthetic can cause a leak if conventional was used before. I just switched to synthetic 25w40 oil this year. Not quite sure what oil was used before because this is my first year owning the boat. I purchase some engine cleaner and will thoroughly clean the engines so hopefully that will help me find the leak easier.

A dock neighbor told you a tall tale. If an engine "consumes" oil it may consume a bit more synthetic. If an engine "leaks" oil it may leak a bit more synthetic. Switching to synthetic does not cause leaks. Synthetic or not, if it is leaking the leak should be fixed. An engine that consumes oil needs a rebuild but that depends on a host of other factors. Some engines consume oil from the "git-go".