Mercury Outboard Lower Unit Oil Capacity: Here Are The Right Capacities

You probably know that if you don’t have enough oil in your Mercury outboard, the engine won’t work right. That means that your boat will be less efficient and might not go as fast as it should. Worse off, it could potentially damage your propeller. That would be bad news for everyone!

So, what’s the right Mercury outboard lower unit oil capacity for your engine? Well, that depends on its model. For instance, 2.5 and 3.5 Mercury engines have a rated capacity of 15.2oz. While you will need 35 oz of oil for an 8 Fourstroke model, Verado models need 211 oz or 246 oz, depending on the model.

However, here is what you need to know about oil capacities for different Mercury engines and much more.

Mercury Outboard Lower Unit Oil Capacity Overview

Imagine you’re out on the water, and your boat is running great. Then suddenly, your engine starts to act up… and it’s not just a little bit! It feels like your motor is seizing up.

So, what do you need to do then? You would probably have some ideas to do something about the noise like giving the engine the right amount of oil!

Well, here is an overview to overcome your headache. Mercury outboard lower unit oil capacity is to keep your engine running at its best. We have listed all the engines, the available models, together with their corresponding oil capacities.

Engine TypeModelsYearsOil Capacity
2.5 and 3.5 FourstrokeAll models with 2.5/3.5 fourstroke2006 to 201915.2oz or 0.48QT
4, 5 and 8 FourstrokeAll models with 4, 5 and 8 Fourstroke1999 to 201915.2oz or 0.48QT
8 Fourstroke232cc1995 to 200035z or 1.05QT
 323cc2001 to 200435z or 1.05QT
 209cc2005 to 201927oz or 0.85QT
9.9 Fourstroke232cc1995 to 19981.05 QT or 35 oz.
 323cc1999 to 20041.05 QT or 35 oz.
 209cc2005 to 20190.85 QT or 27 oz.
15 Fourstroke323cc1998 to 20081.05 QT or 35 oz.
15 and 20 Carb and EFI Fourstroke15 Horsepower2008 to 20191.05 QT or 35 oz.
 20 Horsepower2008 to 20191.05 QT or 35 oz.
25 Fourstroke498cc1998 to 20053.17 QT or 106 oz.
 492cc2008 to 20191.9 QT or 83 oz.
30 Fourstroke747cc1999 to 20053.17 QT or 106 oz.
 492cc2008 to 20191.9 QT or 83 oz.
40 Fourstroke747cc with 3 cylinders1999 to 20193.17 QT or 106 oz.
 996cc with 4 cylinders2001 to 2019 3.17 QT or 106 oz.
50 Fourstroke935cc with 4 cylinders1995 to 2000 3.17 QT or 106 oz.
 996cc with 4 cylinders2001 to 2019 3.17 QT or 106 oz.
60 Fourstroke996cc with 4 cylinders2001 to 2019 3.17 QT or 106 oz.
75 FourstrokeCarbureted2000 to 20055.28 QT or 169 oz.
 1596cc, EFI, and 1B36682220084.8 QT or 160 oz.
 1731cc, EFI, and 1B366823 2B0949952008 to 20145.28 QT or 169 oz.
 2B094996 and above2014 to 20195.5 QT or 176 oz.
90 FourstrokeCarbureted2000 to 20055.28 QT or 169 oz.
 1596cc, EFI, and 1B36682220084.8 QT or 160 oz.
 1731cc, EFI, and 1B366823-2B094995  2008 to 20145.28 QT or 169 oz.
 2B094996 and above2014 to 20195.5 QT or 176 oz.
115 Fourstroke1596cc, EFI, and 1B3668222001 to 20065.28 QT or 169 oz.
 1731cc, EFI, and 1B366823-2B0949952008 to 20145.28 QT or 169 oz.
 2B094996 and above2014 to 20195.5 QT or 176 oz.
150 FourstrokeEFI, 1B905505 and up2011 to 20196.34 QT or 211 oz.
225 FourstrokeEFI2003 to 20066.34 QT or 211 oz.
Verado135 – 4 cylinder2008 to 20196.34 QT or 211 oz.
 150 – 4 cylinder2008 to 20196.34 QT or 211 oz.
 175 – 4 cylinder2008 to 20196.34 QT or 211 oz.
 200 – 4 cylinder2007 to 20196.34 QT or 211 oz.
 200 – 8 cylinder2005 to 20197.4 QT or 246 oz.
 225 – 8 cylinder2005 to 20197.4 QT or 246 oz.
 250 – 8 cylinder2005 to 20197.4 QT or 246 oz.
 275 – 8 cylinder2005 to 20197.4 QT or 246 oz.
 300 – 8 cylinder2007 to 20197.4 QT or 246 oz.
 350 – 8 cylinder2015 to 20197.4 QT or 246 oz.
 400R – 8 cylinder2015 to 20197.4 QT or 246 oz.

How Often Should You Change Outboard Lower Unit Oil?

Like a lot of things, it depends on the person. But generally speaking, when you change outboard lower unit oil, you should do it after every 100 hours of use. The reason is that if you don’t change it often enough (like once every 100 hours), your outboard lower unit won’t operate optimally.

This will cause damage to your engine and make it more likely to fail in the future. So, if you’re using your boat more often, we recommend changing outboard lower unit oil every 100 hours. If you can’t count the hours, ensure you have new oil every year at the minimum.

How to Change Outboard Lower Unit Oil Capacity

You will need the following equipment:

  • Oil resistant gloves
  • New outboard lower unit oil
  • Flat-headed screw drivers
  • A drain pan
  • Replacement o-rings and washers
  • Oil pump for lower unit
  • Cleaning rugs

At first, you need to open the lower unit oil tanks for replacement. Then, use your drain pan to drain the old oil. Now replace it with the new oil and use a funnel to avoid spillages.

Frequently Asked Questions (FAQs)

Here are answers to some of your common questions:

Why is my oil capacity smaller than the indicated alue in the manual?

Some engines will have two vent plugs or more. Consult your manual to ensure that you get the location of all the vent plugs. If you don’t, you might think your oil capacity is smaller than mentioned in this article.

What is the best fuel for the Mercury lower unit?

We recommend Mercury Premium SAE 80W90 Gear Lube for all engines with a rating of below 75 Hp. For the rest of the engine models, use the high-performance variant of the oil. Do not mix the two as it will be catastrophic to your engine.

Can I use any oil for the Mercury outboard lower unit?

No. If you want the best protection, you should only stick to manufacturer recommendations. Your engine will operate optimally when using the right outboard lower unit oil.

Conclusion

All outboard motors need some type of lubricant to operate properly. However, each engine model has a different oil capacity. So it’s important to have the right amount of oil with you when you’re out on the water.

Having too little oil can be catastrophic while having too much can damage your engine or even cause it to fail completely.

In this case, use the Mercury outboard lower unit oil capacity chart in this article to determine the amount of oil your engine needs. Do not go beyond or under the stated capacity for the optimum operation of your boat.

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