[header] How to change your mercruiser engine oil [title] Read your owners manual and its safety precautions. [title] In general, you need to change your oil every year or every 100 hours of use, whichever comes first. [title] Visually inspect your engine and check the oil before starting. 
[title] Make sure the prop has been removed and that no people or pets are near the stern drive or prop before starting the motor. [title] Check for fuel or fuel vapors outside or in a well ventilated area to prevent carbon monoxide poisoning to people.