How To Change the Engine Oil and Oil Filter in a Mercury L6 Verado Outboard

Changing the engine oil and oil filter in your Mercury® L6 200-400hp Verado® outboard* is a simple maintenance procedure that should be performed after every 100 hours of engine operation and at least once a year. Many boaters prefer to include the job in their annual winterization process to ensure the outboard is ready to perform at its peak the following season.

Mercury Service Project Manager Nick Nida outlined the necessary steps for changing the oil and filter in an L6 Verado outboard and provided some expert tips for getting the job done right. Before you begin, Nida suggests reviewing the process outlined in your engine owner’s manual. 

If you’d like to see the process in action, check out this helpful how-to video from our friends at Wired2Fish at the bottom of this blog post.

Essential Tools

Changing the oil and filter requires minimal tools. You’ll need:

• Adjustable wrench or ratchet wrench with 12mm socket for removing the drain plug
• Oil filter wrench
• Funnel
• A few rags
• Crankcase oil pump or oil drain funnel kit
• Oil catch pan for capturing used oil
• Safety glasses and protective gloves
• Outboard water flusher, or muffs, for idling the engine

Choose the Right Oil & Filter

It’s critical to use the correct type and volume of oil as outlined in the engine owner’s manual. For an L6 Verado outboard, Mercury calls for 7.4 quarts of 25W-40 four-stroke engine oil and recommends using a certified NMMA® FC‑W® catalyst-compatible semi-synthetic blend such as premium Quicksilver 25W-40 4-Stroke Synthetic Blend Marine Engine Oil. Pair the oil with a premium Quicksilver 4-Stroke Outboard Oil Filter (Part No. 877769Q01) for the ultimate in performance, protection and peace of mind.

To make it easier to assemble exactly what you need, Quicksilver also offers a convenient oil change kit for the L6 Verado outboard. It includes the appropriate filter and volume of oil, a drain plug seal, an oil drain funnel and instructions.

All Quicksilver four-stroke engine oils are compatible with outboards from leading marine manufacturers and will not void manufacturer warranties. They’re also enhanced with additive packages formulated specifically to protect marine engines from wear and corrosion during use in harsh environments. That’s just part of what has made Quicksilver the most recommended brand of marine engine oil by marine service professionals for the last five years.

Safety Precautions

The job of changing the oil and filter in your outboard has minimal safety risks. However, Nida recommends wearing protective gloves and eyewear and pulling the emergency stop switch to disable the engine while you work.

Also, be sure to transfer the used engine oil into an oil-safe container and to dispose of it properly. Some municipalities accept used oil at recycling and garbage collection centers. Many automotive parts retailers also collect used oil for recycling.

The Procedure

1. Drain the oil
2. Trim the outboard out past vertical for approximately one minute to allow any trapped oil to drain out of the valve cover and into the oil sump.
3. Trim the outboard back to vertical and remove the engine cowl.
4. If you’re using an oil pump, be sure to review the instructions to make sure it is configured correctly. Then remove the dipstick and insert the pump’s oil extraction tube into the dipstick hole until the tube reaches the bottom of the engine oil sump. If you’re not using an oil pump, locate the drain plug beneath the splash plate on the port side of the outboard. Position the oil catch pan under the engine. Then loosen (but don’t remove) the plug and install the oil drain funnel over the drain port.
5. Pump the oil into an oil-safe container. If you’re not using a pump, remove the drain plug to drain the oil into the catch pan.
6. Be sure to clean and reinstall the drain plug once the oil finishes draining.

Pro Tip: Check for Signs of Contamination

Always inspect your engine oil for signs of water or fuel contamination. Oil contaminated with water will have a milky color. Oil contaminated with fuel will have a strong odor of gasoline. If either sign is present, consult an authorized service technician.

1. Change the filter
2. With the engine cowl removed, locate the oil filter on the starboard side of the outboard.
3. Place a rag or towel below the filter to absorb any spilled oil. Then use an oil filter wrench to remove the filter by turning the filter counterclockwise.
4. Use the rag to wipe up any residual oil on the oil filter mounting base.
5. Use your finger to spread a small amount of new engine oil on the rubber filter gasket of the new oil filter.
6. Thread on the new filter until the gasket contacts the base.
7. Tighten the filter an additional three-quarter to one turn using the oil filter wrench.

Pro Tip: Don’t Overtighten

Before seating the filter, take note of a letter, symbol or other mark on the filter case to use as a reference while tightening it down. Track the mark as you tighten the filter to be sure you don’t make more than one full turn.

1. Add new engine oil
2. Double-check that the oil drain plug is in place. Then remove the oil fill cap and use the funnel to add the new oil. To avoid overfilling, start by adding 7 quarts.
3. Reinstall the oil fill cap.
4. To check the oil level, first trim the engine out past vertical for one minute to allow oil to drain back to the oil sump.
5. Now pull out the dipstick, wipe it clean, reinsert it and pull it out again.
6. Check that the oil falls within the operating range indicated by the crosshatching on the dipstick. If it’s below the crosshatching, add a small amount of oil and check again. Repeat the process until the oil level is within the acceptable range. There’s no need to fill the oil to the upper end of the operating range.
7. Use an outboard water flusher, or muffs, connected to a hose to safely idle the engine for five minutes so you can check for leaks at the oil filter.

That’s all there is to it. Protecting your engine – and your peace of mind – is as simple as following these steps and incorporating premium Quicksilver marine lubricants and filters into your annual maintenance procedures.

*The process for changing the oil and filter in an L6 200-400hp Verado outboard varies from a V8 250 or 300hp Verado outboard. Consult your owner’s manual for detailed instructions.

NMMA and FC-W are registered trademarks of the National Marine Manufacturers Association, Inc. All other trademarks belong to Brunswick Corporation.