Yes, you are correct, there are 2 places you may add your oil in a 2305. The reason is as Kenny states. This engine is used in many applications where access may be limited to one of the fills. The 2520 is the same way.cleaning the engine, does the 2305 have 2 places where you can add engine oil? see a yellow cap on the top of the engine and one on the side by dip stick. Why and any difference between the two?? Thanks