How to Change the Oil on Your Outboard Motor – The Right Way
By Christian – Boat Max Online
Whether you're staying on top of regular maintenance or getting your boat ready for the season, changing the oil in your outboard is one of the most important steps you can take to keep your engine running strong.
In this guide, I’ll walk you through how to change your outboard oil the right way, using a Suzuki outboard as an example—but these steps apply broadly to many modern four-stroke outboards.
What You’ll Need:
Make sure you’ve got all the tools and materials before you start:
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Socket wrench
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Hook or pick
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Pliers
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Flathead and Phillips head screwdrivers
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Oil extractor pump
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Handheld gear oil pump
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Manufacturer-recommended oil
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New oil filter
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O-ring for oil filter cover
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Lower unit drain plug gaskets (2 total)
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Oil pan
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Clean rag or paper towels
Step-by-Step: Outboard Oil Change
1. Remove the Cowling & Panels
Start by removing the engine cowling. Then take off the rubber gasket and use an 8mm socket to remove the side panels. On models with power trim and tilt, you’ll need to access a tight plug—this can be done by hand, but a pick makes it much easier.
You’ll also want to remove the fuel filter to gain better access to the oil filter. Some hoses can stay in place, but removing them will make everything more accessible.
2. Remove the Oil Filter
Use a 10mm socket to take off the oil filter cover, then remove the old oil filter. Be careful not to spill any residual oil in the process.
3. Extract the Old Oil
Remove the dipstick and insert your oil extractor hose into the dipstick tube. Begin pumping the old oil out until it's completely drained.
Pro tip: Without an extractor, you'd have to drain it from the midsection, which is much messier.
4. Install the New Oil Filter
Insert the new oil filter and replace the O-ring on the filter cover. When re-installing the cover, make sure the arrow is pointing downward.
Reattach any hoses or panels you removed earlier.
5. Refill With Fresh Oil
Using a funnel, pour in your manufacturer-recommended oil. In this example, we’re using Suzuki Ecstar 10W40. Check your outboard’s oil label (usually on the motorhead) to verify the correct oil type and quantity.
Reinsert the dipstick and confirm the oil level is within range.
Now Let’s Change the Lower Unit Gear Oil
1. Drain the Lower Unit
Position an oil pan underneath the lower unit. Remove both the top and bottom screws—you can use either a Phillips head or flathead screwdriver.
Let the gear oil drain completely. Check for any metal shavings or signs of contamination.
2. Refill With Fresh Gear Oil
You’ll need:
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Suzuki Ecstar Gear Oil
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Two new lower unit gaskets (one for each screw)
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A handheld oil pump
Screw the fitting into the gear oil bottle and attach the yellow tip. Then screw that into the drain hole and begin pumping. Stop when oil starts to flow from the top hole.
Quickly install the top plug and gasket, then the bottom plug and gasket.
That’s It! You Just Gave Your Outboard a Fresh Start
Regular oil and gearcase oil changes help extend the life of your engine, improve performance, and reduce the risk of costly repairs.
All tools and products used in this tutorial are available at BoatMaxOnline.com.