Sterndrive Maintenance Tips

Published on January 10, 2022


While car engines get harder for owners to work on, the opposite is true for MerCruiser sterndrives

Despite the increasing popularity of outboard engines, for many boaters who are into watersports or lounging at the sandbar, nothing beats a sterndrive-powered boat. The major benefit is the ability to have a wide-open swim platform that makes it easy to hop into the water or sit with your feet in the water while watching the sunset.

The other benefit for shade-tree mechanics who are into DIY boat maintenance is the motors closely resemble those found under their car’s hood. But unlike newer cars, which have increasingly DIY-unfriendly configurations, modern MerCruiser engines are purpose-built marine engines that are designed by Mercury to have service points that are easily accessible. This helps those who own Sea Ray boats to be able to handle many of the routine sterndrive boat maintenance items themselves.

MerCruiser makes it easy to keep up with scheduled maintenance with add-on features like VesselView, which is a plug-in device that sends a wealth of information via VesselView Mobile to a smartphone or a boat’s multi-function display. Not only does it inform the user of all engine parameters like speed, rpm, fuel consumption and all sensors like oil pressure, water temperature and voltage, VesselView also sends a warning if something is amiss. In addition, it also keeps track of engine hours and will send a notification to the user and dealer, if desired, giving information when to service the boat engine. On 4.5L and 6.2L sterndrives, a handy sticker shows a host of information like what fluid levels should be periodically checked and also displays a complete maintenance schedule.

Changing the Engine Oil
MerCruiser has a series of videos on YouTube that walk boaters through some of the easier service items a boater can handle on their own. Changing the engine oil is made easy by a couple of innovations. The first is a Mercury/Quicksilver crankcase pump that attaches to the dipstick tube that pumps the old oil into a container. Another clever system uses a drain hose connected to the boat’s drain plug for easy passage through the drain hole that can be unscrewed at the end to dump the old oil.

Before changing the oil, run the engine for about 5 minutes to warm the old oil and then remove the oil fill cap to introduce air into the system before draining. And don’t forget to change the oil filter, which can be done more easily if you punch a small hole in the top with an ice pick to ventilate it to allow it to drain the oil within. Smear fresh oil around the seal of the new filter and hand-tighten it only. Fill with Mercury/Quicksilver 25W-40 Synthetic Blend (4.5 US qt for the MerCruiser 4.5L, 5 US qt for the 6.2L). Always change the oil before storing your boat for the winter.

Changing the Gear Oil
MerCruiser gear oil should be changed at least every 100 hours and at the end of the season to make sure impurities or metal shavings don’t adhere to the gearcase’s interior. The procedure is easy to perform as demonstrated online by Mercury master mechanic Kevin Muth. First, trim up the outdrive all the way and slide the drain pan underneath to catch the old oil. On 4.5L and 6.2L sterndrive models, remove the gear oil monitor cap to vent the system before using a flathead screwdriver to remove the upper vent screw on the outdrive. Then, remove the lower drain screw and trim the outdrive down. While the outdrive is draining, fit the pump to a bottle of Mercury High Performance Gear Oil. After draining, screw the upper vent screw into place, screw in the pump nozzle into the lower drain screw hole and pump until it reaches the proper level in the oil monitor tank. Make sure to use a new gasket on the lower drain screw for a perfect seal.

Other Easy DIY Projects Worth Trying

·         Using the Single Point Drain feature

·         Changing spark plugs and wires

·         Keeping grease fittings lubricated

·         Replacing your sterndrive’s sacrificial anodes

While you can do your own sterndrive winterization, Mercury recommends letting your dealer handle this critical task since if not done properly, any resulting damage won’t be covered by the warranty.


This is for general information purposes only. Your use or reliance on any of the information in this Blog is solely at your own risk. Under no circumstance will we have any liability for any loss or damage of any kind incurred as a result of the use of any of the information provided.

Options and features mentioned subject to change. Please confirm availability of all accessories and equipment with an authorized Sea Ray dealer.

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