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How To Perform 100 Hour Service On Mercury Verado L6 300-400HP Engine!

By Jonathan Matthews on

When it comes down to it, maintenance is one of the most important aspects of owning a boat. Without diligent preparation and understanding, you can negatively effect your time on the water in a big way. Engines are the lifetime for your boat, as this is the main propulsion unit to get you off the dock and to your destination.

For Mercury Verado owners, the history of consistent performance is there -- but our team of technicians have some tips to make your life easier, and possibly save you some money in the long run! The most important maintenance reminder happens in the 100 hour range on these engines. The manufacture calls for change of both engine & gear case fluids (with seals), and a in-line fuel filter change. If you are running your engine hard, or have a 400HP model -- we also suggest replacing the serpentine/supercharger belt during this process.

Why do you suggest 25W-50 instead of 25W-40? As stated in the manual, these engines take 25W-40, as well 25W-50 in hotter climates. Living in South Florida, the majority of dealers use 25W-50 as a standard. The 25W-50 allows for a wider range of temperature variance and provides a more consistent fluidity in variety of conditions. This variance can be confusing, but our technicians suggest using 25W-50 for any of the supercharged engines. This is what is used in the 450R 4.6L V8 engines now, as well.

Other maintenance tips for Verado owners: 

  1. Keep all electrical connections, battery terminals, and grounds clean of corrosion. This can be done with generic silicone based spray or CRC. 
  2. Inspect upper and lower rubber cowling seal for folding and damage. You can also apply silicone spray to prevent from drying/corrosion.
  3. Make sure proper flow is present out of engine cooling system (engine is peeing).
  4. Look for corrosion and leaks in all trim/tilt rams. Signs of oil leaks may indicate broke seals or failure of internal pieces. 
  5. Use gas from reputable marina/gas station -- this is one of the most important pieces of advice we can have. We constantly see low quality gas on the water and this can negatively effect not only the Verados performance -- but also add water into the system which can be catastrophic. 

How To Perform 100 Hour Service on Mercury Verado 300-400HP engines:


⚙ Parts Used: 

⚙ 100 Hour Service Includes Following Parts:


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