Need to add some oil to the boat and I'm not sure if the person before me was running synthetic. Would it be a problem it I added the wrong oil type (weight, brand) or should I just get it changed?? I was thinking of just putting some standard oil in it.

SC

Synthetics and petroleum based oils can be combined without any problems.

If you need to add oil, it is probably time to change it. Then you would be sure of what type is in the engine.