Category: Boating Knowledge Base

Mercury Verado Oil Change Instructions


The step by step how-to-video below will walk you through the process of changing the oil in your 6-cylinder Mercury Verado outboard engine. Learn from one of Mercury’s Experts, how to change the engine oil. For more information regarding your Verado, please consult your Mercury Marine Verado owner’s manual. 

What You Will Need

This video is courtesy of Mercury Marine. Original video can be found at

Mercury Marine Four Stroke Maintenance


Whether you outfit your rig with a TwoStroke or FourStroke outboard depends on the type of boat you’re running and what your performance needs are on the water. What’s much more cut and dry is the difference in routine service schedules between the two. If you’re considering a FourStroke and want to learn more about how to keep it performing optimally, whether your maintenance is done at home or by a professional, the steps outlined here should help out. We consulted members of the service crew at Toho Marine and Outdoors in St. Cloud, Fla., one of the country’s largest bass boat dealers, for the basics. Luckily, there are some industry standards (and rough guidelines) to follow when it comes to FourStrokes, but some of the specifics vary by make and model. If you decide to tackle it yourself, you’ll want to consult your dealer to make sure you’re following the proper maintenance procedures. And, it’s never a bad idea to simply rely on the dealer to do the maintenance for you. If that’s the route you go, you’ll understand the basics and know what services are being provided after reading this.

Change Engine Oil

If your new FourStroke has been broken correctly (according to Mercury recommendations) and operated for a few months under normal bass fishing conditions, the first maintenance usually occurs at the 100-hour mark. At that time, the engine oil and oil filter should be changed. Only use factory-recommended parts and lubricants such as Mercury Precision Parts. Although FourStroke engines perform similar to, say, an automobile, their needs are drastically different. For example, the oil must be able to withstand extended high RPM. Changing oil is simple. A drain screw is located on the lower gearcase. A special wrench may be needed for the oil filter located beneath the cowling, but it, too, can be easily removed and replaced. Don’t over-tighten when you replace it, and refill with the appropriate amount of oil.

Change Gear Oil

Along with an engine oil change, owners should also change gear oil at 100 hours. The drain and vent screws for this may be located on the lower unit, or possibly behind the prop. In any case, both must be removed to allow all the gear oil to drain. Check the oil for any discoloration (milky means water has entered the gear case) or metal pieces. The drain screw is also magnetic; check it for shavings that could indicate a gear problem. When refilling, gear oil must be pumped back in through the drain hole until it comes out the vent. Wait five minutes and pump a little more in to ensure it’s filled to capacity.

Change Fuel Filters

Fuel filters require initial 100-hour maintenance as well. Large four-stroke outboards include a fuel/water separator filter in the bilge area of the boat. This can be easily changed and should be during this initial service.  The Mercury Verado also includes an additional pressurized filter that should be serviced by a dealer, but not until 300 hours.

1-Year Maintenance

Usually, after one year, it’s time for the outboard’s second scheduled maintenance. At this point, engine oil and filter, gear oil, and fuel filters should be changed again. In addition, the water pump should be inspected, and the impeller should be changed by the dealer (while the impeller may be in good shape, simple pump inspection requires substantial labor cost, so the part is changed for preventive purposes). In addition, spark plugs should be inspected and changed as needed. Good plugs will have a bronze coloration and sharp edges. Additionally, some dealers such as Toho Marine will perform further tests as part of their regular 100-hour service, including a computer diagnostic to check for codes that might indicate operating errors, and make sure the motor is firing efficiently. Further service also includes a compression check to ensure there’s no advanced carbon build-up or ring problems within the motor. As discussed, check your user manual for recommended 300-hour inspections and filter changes, as well as belt service at 1,000 hours.

More Advice

A number of other service items can reduce headaches on the water:

1. Use fuel additives whenever possible, and stabilizer when needed, to reduce carbon build-up and fight the problems created by ethanol.

2. Fight corrosion on battery terminals with terminal cleaner.

3. Spray down the cowling seal with a silicone spray to keep it supple and watertight.

4. Visually inspect the power trim and tilt rams and seals for any leaks, and retract the rams all the way in during extended periods of non-use.

5. Each spring, inspect the cooling system outflow hole on the side of the motor to ensure it’s not clogged.

6. Finally, the best tip for any of today’s outboards: Buy gas at a busy station, and do not allow it to sit in your tank for more than a few months.

Original Article found in Mercury Marine’s Blog Site. You can read the original article, written by Joe Balog on the Basic upkeep of a Four Stroke Outboard Motors at[]=how-to.

Checking Power Trim Fluid


Keep your engine in peak condition by checking and changing your power trim fluid when necessary. This is a very important maintenance step.

Mercury Marine – Checking Power Trim Fluid

This video and others like this video can be found on Mercury Marine’s Blog. You can find this original content on

Precision Oil & Lubricant Guide


Boating is not often thought of as a harsh environment, but it is one of the most demanding environments in which an engine can operate.

Marine engines can and are often used for extended periods at wide-open throttle (up to 6400 rpm on some models), in harsh saltwater, and intense UV sunlight. Then, marine engines sit in storage over the off-season, in many cases without any use. Focusing on these demands, all Mercury Marine Precision Oils and Lubricants are specially engineered for the unique needs of marine engines and rigorously tested to meet our high standards, protecting your outboard and providing many years of engine life.

Mercury Precision Lubricants

Two-Stroke Marine Oil

Premium Plus Two-Stroke High-Horsepower Outboard Oil

Specifically formulated with a higher concentration marine additive package to meet the needs of high-horsepower outboards including direct-fuel-injected engines in extreme marine operating conditions. Far exceeds Mercury in-house test standards, which are more stringent than the industry’s TC-W3 standard. Cleanest burning, reduces carbon build-up in exhaust system and superior lubrication. Meets all outboard and personal watercraft manufacturers’ recommendations for use of TC-W2 and TC-W3 oils in pre-mix or oil-injected 2-cycle applications. Provides warranty protection for Mercury, Mariner, Force and Sport Jet and M2 Jet Drive 2-cycle engines.

OptiMax/DFI 2-Stroke Outboard Oil

A synthetic blend 2-Cycle engine oil specifically formulated and developed to meet the needs of OptiMax and Direct Fuel Injected (DFI) 2-cycle outboard engines.  Provides the maximum protection for OptiMax and DFI engines even under the most extreme operating conditions. Outperforms other oils by combining a carefully modified base stock blend with a synthetic additive package. Minimizes carbon build-up to help maintain engine top end speed and acceleration. Superior lubrication for increased resistance to piston scuffing. Will mix with typical 2-cycle engine oils. Provides warranty protection for Mercury and Mariner OptiMax and DFI outboards.

Premium 2-Cycle Outboard Oil for Low to Mid-Horsepower Outboards

Specifically formulated with a marine additive package to meet the needs of low- to mid-horsepower outboard engines operating under general marine conditions. Exceeds TC-W3 standards. Reduces rust and corrosion of internal components. Meets all outboard and personal watercraft manufacturers’ recommendations for use of TC-W2 and TC-W3 oils in pre-mix or oil-injected 2-cycle applications. Provides warranty protection for Mercury, Mariner, Force and Sport Jet 2-cycle engines.

Mercury Precision Lubricants

FourStroke Marine Oil

FC-W FourStroke (25W-40) Oil

Mercury’s FourStroke oil technology outperforms automotive oils in marine applications because of its specialized additive package designed for marine engines. 25W40 is recommended for all marine engines.

Things to know about this oil:

  • For use in all four-stroke marine engines. This oil is engineering approved for all marine four-stroke applications including outboard, MerCruiser, high performance, sterndrive/inboard. Exceeds all marine industry four-stroke oil requirements including FC-W and FC-W compatibility.
  • Outstanding engine and corrosion protection – industry leading strength and viscosity retention and ultimate corrosion and wear protection.
  • The most recommended marine oil. More than 5 years of development work by the largest marine manufacturer in the world.

Synthetic Blend 4-Stroke (25W-40) Outboard Oil

A technology specific 25W-40 marine oil formulated for the world’s first and only supercharged and inter cooled outboard engine. The unmatched torque and acceleration of the Mercury Verado engine requires maximum protection found in this well-balanced combination of today’s highest quality synthetic and mineral base stocks. Mercury 25W-40 Synthetic Blend Outboard Oil meets the stringent marine operational requirements of all of Mercury’s new 4 and 6 cylinder models. First in class for all FC-W durability test properties with industry leading internal Marine engine corrosion protection.

25W-40 Synthetic Blend Oil shows significantly better shear stability and volatility, and is higher in viscosity and High Temperature High Shear (HTHS) after shear. The popular competitive formulation uses a fair amount of VM (viscosity modifier) which is subject to shear, while the Mercury oil contains no VM. As a result, the Mercury oil will hold its viscosity far better in high-revving and long-running situations when the engine needs it most. The HTHS after shear follows along with the viscosity stability, which also results in improved bearing protection.

FourStroke (10W-30) Outboard Oil

Specifically formulated and developed to meet the needs of all four-stroke outboard engines. Developed for the rigors of the marine environment. Industry-leading corrosion protection. Features premium-grade synthetic and mineral-based stocks with specially designed marine grade additives not required in automotive oils. Outstanding lubricity for internal engine components to reduce wear, scuffing and scoring. Excellent running quality and long-term reliability. Rigorously tested to guarantee warranty protection for Mercury and Mariner four-stroke outboards.

Mercury Precision Lubricants Gear Lube

Premium Gear Lube – Lower Units for Outboards Below 75 Horsepower

Mercury Marine gear lube outperforms automotive gear oil in marine applications because of its specialized additive package designed for marine gear cases. Continued use of this gear case lubricant will: Provide maximum protection against excessive wear – even in the presence of water prevent corrosion and pitting. Mercury Premium SAE 80W90 Gear Lube is recommended for lower units for outboards below 75 horsepower. Mercury Premium SAE 80W90 Gear Lube should not be mixed with Mercury High-Performance SAE 90 Gear Lube.

High-Performance Gear Lube

Engineered to provide maximum protection for sterndrive and outboard lower units. Exclusive formula is engineered to
provide extended gear life in extreme conditions including high-speed and high-horsepower applications. Extensively tested to provide excellent protection against corrosion and excessive wear. Specifically formulated to help prevent failures due to water entering the gear housing. Extreme pressure synthetic additives protect gears from metal to metal contact. Since no industry-wide standards exist concerning marine gear oils, it is essential to use products such as Mercury High-Performance Gear Lube which has been specifically designed and tested for marine applications. DO NOT mix with Mercury Premium Gear Lube. Provides warranty protection for all Mercury MerCruiser sterndrive and Mercury, Mariner and Force outboard lower units.

Mercury Precision Lubricants Diesel Engine Oil

Diesel (15W-40) Engine Oil

Specifically formulated and developed to meet the needs of all marine diesel engines, including Mercury MerCruiser D-Tronic. Contains a higher additive level than standard fleet oils, providing greater protection. Provides excellent wear tolerance. Provides excellent shear stability to assure stay-in-grade performance. Protects the internal engine components from corrosion and wear. Helps control the formation of sludge and varnish deposits, even in highly stressed applications. Provides warranty protection for Mercury MerCruiser Diesel engines.

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