I put Kieth Eikerts pre lubers in the 41. To change the oil all you do is plug in the drain hose and flip the swithch. If you use a long enough hose you can actually leave the oil container outside of the boat. When you're done simply unplug the hose and refill with oil. It might cost alot in the beginning but as far as I'm concerned it's the only system to have. It will be in all my future rides Good luck in your decision on oil changers kook.