I am the relatively new (couple months) owner of a Mainship 40 with twin Yanmars. Getting ready to do an oil change. Each engine has a gray plastic/rubber hose fitted to the oil pan. They are a couple feet long and just have a plastic plug shoved into the open end. Is an added on item or was this a factory option? More importantly, will I be able to gravity drain the old oil or will I need some type of pump assist. Looks like I can get a container to sit in the bilge lower than the oil pans. Not 100% sure since the bilge is not flat. Not sure how low the catch container will actually sit. Anyone got this similar system or familiar with it? That plastic plug just pushed into the open end is a little scary to me but surveyor or my agent never commented on it. Thanks in advance this site has been very helpful to a new owner.