Quicksilver 25W-40 4-Stroke Conventional Inboard Sterndrive Marine Oil Protect your boat engine during the winter months using best practices that include the use of Quicksilver 25w 40 Marine Engine Oil. Marine engine technicians report that engine oil that is left untreated when the boat is drydocked or in off-season storage, are the leading cause of hard-starting and other common engine performance issues in todays watercraft. This superior Quicksilver 25w 40 Marine Engine Oil has been specif