Hi Pat, we need to know what kind of engine is fitted to your SB590. I believe they usually had a Briggs & Stratton, but having the right amount of the right oil is rather important, so we should identify the engine with certainty before going further. Please post a couple of pictures, one showing the whole engine, and the other showing the oil filler. If it is a Briggs engine, please tell us the Model, Type and Code: these will be stamped on the cooling air cowl, probably above the muffler.
