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Best 4 Stroke Outboard Motor Oil – (Reviews & Guide 2021)

When it comes to keeping the motor of your boat running nice and smooth, you will have to ensure that you use quality motor oil. The wrong oil might just cause your motor to malfunction prematurely – and with poor maintenance, there is a chance that even your engine warranty will not save you. For this reason, you will have to ensure that you only purchase the best 4 stroke outboard motor oil.

Having said that, how do you even begin to choose a good brand? Oil is just oil, right? All types should work. Well, that is not precisely true. This is exactly why we have put together a few good reviews along with some buying advice so that you may only purchase the right product.

Best 4 Stroke Outboard Motor Oil Comparison Chart

YamaLube All Purpose 4 Four Stroke Oil 10w-40 1 Gallon

YamaLube All Purpose 4 Four Stroke Oil

  • Price: $
  • Size: 1 Gallon
  • Provides: Stable clutch performance
  • Viscosity: 10W-40
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Quicksilver 4-Stroke Marine Engine Oil

Quicksilver 4-Stroke Marine Engine Oil

  • Price: $
  • Size: 1 Gallon
  • Provides: Great strength, along with viscosity retention
  • Viscosity: 25W-40 
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MERCURY 4-Stroke Engine Oil

MERCURY 4-Stroke Engine Oil

  • Price: $$
  • Size: 1 Gallon
  • Provides: The noise is kept at a minimum
  • Viscosity: 25W-40 
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Yamaha Yamalube 10W30 MARINE Oil

Yamaha Yamalube 10W30 MARINE Oil

  • Price: $$$
  • Size: 1 Gallon
  • Provides : Protective layer
  • Viscosity: 10W-30
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Best 4 Stroke Outboard Motor Oils Reviewed (UPDATE LIST)

1. YamaLube All Purpose 4 Four Stroke Oil

YamaLube All Purpose 4 Four Stroke Oil 10w-40 1 GallonIf you are looking for high-quality oil that can withstand winter use, then this 10W-40 viscosity grade oil can do quite a good job. While it might also be used during the summer and has very good resistance to high motor temperatures, this oil can easily withstand low temperatures of winter.

Since the product is made on a mineral oil base, it provides quite a stable clutch performance. This should protect your engine from further wear and tear – prolonging its life. Plus, aside from your boat, this motor oil can also be used on a variety of other engines, such as your car, your motorcycle, your ATV, and so on.

Since this is mineral oil, its price is also quite attractive. That being said, its quality is quite superior – particularly since it is a popular brand. It is also sold in a one-gallon canister, so it will surely last you for quite a while.


  • Features quite a high longevity in comparison to other motor oils
  • Viscosity makes it suitable for both high and low temperatures
  • Efficient in maintaining the correct friction and film between clutches


  • The price is quite high

2. Quicksilver 4-Stroke Marine Engine Oil

Quicksilver 4-Stroke Marine Engine OilIf you are looking for a 4 stroke motor oil that can help your engine withstand wear and tear, then this is a product that you might want to look at. Formulated exactly to help you in that purpose, this is perfect for any four-stroke engine.

The reason why people appreciate this oil so much is because it provides great strength, along with viscosity retention. Featuring a 25W-40 viscosity, not only can it withstand summer use, but it can perform very well in winter as well. It can keep the motor running smoothly, but also protects it when idle.

The price is also very attractive, considering the quality that this product shows. Granted, it’s not as cheap as other mineral brand oils out there – but it’s still more affordable considering its longevity. It should help your engine run at top speed for quite some time – protecting its longevity.


  • Very efficient at keeping the motor silent
  • The price is very convenient, considering its quality
  • Can withstand low temperatures very well due to its viscosity
  • Very efficient for high-hour engines that have a low idle oil pressure


  • The product description might be inaccurate, as it comes in a single bottle instead of packs of three

3. MERCURY 4-Stroke Engine Oil

MERCURY 4-Stroke Engine OilIf you are looking for something that is slightly more on the affordable side, then you might want to try the Mercury 4-Stroke engine oil. People actually recommend that if you buy the gallon, you will actually save much more money than buying the quarts.

Due to its viscosity, people mostly recommend it for undergoing winter service. Most reviewers say that you should not skimp on the oil, because the more you add, the better the engine should be able to perform. It will allow your 4-stroke engine to purr as you are speeding on waters – ensuring that the noise is kept at a minimum.

The quality of the oil is also quite superior. The oil might not be purely synthetic, but at the same time, it is durable. You should be able to go quite a long time between oil changes with this product, making it a convenient purchase for those that do not like to spend all of their time on maintenance.


  • Sold at quite an affordable price
  • Perfect for winterizing your motorboat
  • Quality oil that prevents the motor from damaging prematurely


  • The only complaints are that sometimes, the delivered product does not match the ordered one

4. Yamaha Yamalube 10W30 MARINE Oil

Yamaha Yamalube 10W30 MARINE OilWhen it comes to purchasing quality 4 stroke outboard oil, it is always a good idea to go with a brand name – and Yamaha has proven time and time again that it can be reliable. Perfect not only for your 4-stroke engine but also a variety of other engines, this oil provides a protective layer that might protect your unit for a long time.

Thanks to its viscosity, this product is very efficient for summer use – but it is good for winter use as well. This way, if you wish to winterize your boat, then this is likely the product that you might want to choose.

Considering that it is brand oil, it’s not the cheapest out there – but at the same time, it is not the most expensive either. In fact, you may say that the product is quite an investment, considering the quality that it brings.


  • The quality of the oil is superior
  • Perfect for a variety of 4-stroke engines
  • Affordable yet effective


  • Some complain they did not receive the oil as advertised

Important Features to Focus on When Getting a 4 Stroke Outboard Motor Oil

Best 4 Stroke Outboard Motor OilWhen buying a good type of 4-stroke outboard motor oil, you need to keep in mind a few crucial features. Some of the most important include:

1- Purpose

When purchasing motor oil, make sure that it is precisely made to withstand the 4 stroke motor. Indeed, there are some oils that can work on pretty much any type of vehicle motor (which includes boats), but there are also those that have been made specifically for bicycles or cars. Plus, if you have a 4 stroke motor, then you clearly cannot buy 2 stroke outboard oil. Make sure that you only get the right kind.

2- Quantity

Exactly how much motor oil do you want to purchase? The standard comes in a 4-gallon canister, but you may also purchase larger packs depending on how much motor oil you need. However, bear in mind that motor oil might lose its efficiency if it has not been used for quite a long time – so, you might want to refrain from “stocking up for rainy days.” Only purchase large canisters if you have multiple engines to oil up.

3- Type

You should know that there are three types of 4 stroke outboard motor oil to go for: synthetic, mineral or semi-synthetic – which is a combination of the two. Here is what each type brings to the table:

  • Mineral/Conventional Oil

Mineral is likely the standard option that is used on pretty much any type of engine. Basically, mineral oil is refined petroleum oil that has also undergone treatment to function well at high temperatures. It also gets fortified with quite a lot of additives to function, and it has a lower price in comparison to other oil types. The disadvantage here is that you may have to change the oil often, as it tends to run out or get burned quite soon.

  • Synthetic Oil

In a way, synthetic oils are mineral oils – or at least, that’s what they started out as. Unlike conventional oil, this type of oil goes through even much more extensive treatments – making it the superior type of oil. During the treatment, the impurities are also mostly removed, resulting in high-quality oil that can better withstand high temperatures.

Since the process of breaking down the minerals is fairly complicated and expensive, the buying price is also quite high. That being said, this oil can better withstand both hot and cold temperatures. This means that it will get used up much slower and it will not freeze up as easily during winter.

  • Semi-Synthetic Oil

Semi-synthetic oil is a type that blends both synthetic and mineral oil – making it of a higher quality than conventional oil, but less expensive. Since synthetic oil is added to the mineral kind, the viscosity will also increase – along with the resistance to wear. Based on your requirements, synthetic oils have quite a good ability at performing at both high and low temperatures – with the highest efficiency being when the weather is cold.

In the end, the standard 4 stroke outboard motor will not require that you necessarily use synthetic oil or the semi-synthetic kind. If the mineral oil is of high quality, then it should work just fine for your boat as long as you replace it at the recommended intervals of time.

However, if you are planning to use your boat for performance purposes, or regular long boat rides, then you might want to invest in quality synthetic or semi-synthetic oil. This way, you will be putting less pressure on the engine, boat battery motor – and let’s admit it, your boat will love it.

4- Engine Power

Some kinds of motor oils work much better with certain engine powers. So, before you make your purchase, make sure that yours can withstand the power of your engine. In most cases, it should be written on the label – but if it isn’t, then it might be a good idea to contact the manufacturer and pose the question to the makers themselves. For more info about engines, you might want to visit our home page.

5- Viscosity

The higher the viscosity of the engine oil that you are planning to purchase, the higher its resistance to flow will be. That being said, you will also have to choose the viscosity based on the season that you are planning to use the boat. If the oil’s viscosity is marked with a “W,” it means the product has been tested in winter use. A 10W-10 grade is one oil example that may be used during winter, whereas 5W-30 grade is better used for summer.

During winter, it might be more appropriate to use 4 stroke engine oils that have a lower viscosity. On the other hand, if you are planning to use the boat only in the summer, then you might want to go for the engines that have a higher viscosity, capable of withstanding 100+ degrees Celsius.

6- Price

When it comes to purchasing 4-strike outboard motor oil, you need to be mindful of the price. You do not have to spend a lot of money on a few gallons of oil – but that being said, you should not go on the cheapest option either. If you have a high-performance speed boat or are planning to travel long-distance with it, then you might want to consider investing in higher-quality (but more expensive) oil. On the other hand, if you have a small outboard motor boat that you are only using for the occasional fishing trip, then the average-priced oil should work just well.

Final Thoughts

Finding the best 4 stroke outboard motor oil might not be such an easy task to deal with – but as long as you pay attention to the right factors, it is not impossible either. You just have to read the product description, as well as a few reviews from people that have previously used it, and you will know whether the choice you made is the right one or not.

Hopefully, our guide managed to give you some insight into what kind of 4 stroke motor oil is best for you. Remember that quality is very important here – particularly if your boat is a professional one.

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