How Often Should You Change the Oil in Your Boat’s Engine?


Hello and welcome to, the place where true boaters and sailors go to learn and find inspiration.

Today, we’re going to tackle a question that many of our readers have asked – just how frequently should you change your boat’s engine oil?

 Well, read on to discover the answer to that and other questions.

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Why change your boat’s engine oil?

Perhaps, before you learn how often to change the oil, you should learn the importance of changing it in the first place.

Dirty engine oil contains grit, which wears the engine’s precision surfaces if the oil is not removed. It also contains acids, which dissolve the internal parts of the engine.

By changing the oil frequently, the harm is drastically slowed, thus extending the engine’s life by thousands of hours.

The oil is the engine’s lifeblood, and if it’s not being renewed regularly, irreversible damage looms.

This is especially true during winter, as the moisture and the residual acids left in the crankcase during this time can corrode bearings and other critical parts of the engine.

That is why it’s normally recommended that you change the oil before you lay up for the winter and any other time that you expect the car to lay idle for an extended duration.

So, how often should you change the boat’s engine oil?

Every 50 to 100 hours is the frequency that most boat manufacturers recommend for both diesel and gasoline engines. But, it’s crucial that you check the user manual for your boat’s exact frequency.

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Is your boat engine brand new? 

Then, it’d be better to change the engine oil more frequently for the first 100 hours, like every 20 hours or so. As the engine gets older, the internal parts will get tougher, and they will require less frequent oil changes.

A filter harbors lots of oil, and therefore, failing to change the filter is a lot like poring today’s tea over a quarter cup of yesterday’s tea. 

Therefore, when changing the oil, it’s sensible that you change the filter as well.

Things to Keep in Mind When Changing the Boat’s Engine Oil

It’s always advisable to run the engine prior to changing the oil. That way, it’s able to warm adequately and gain a better flow.

Make sure to stop it, otherwise it will harm the boat battery. The contaminants also get suspended in the oil, rather than lying at the bottom. If you were to drain the oil cold, plenty of the contaminants would stay behind. 

As a good-quality oil filter is good for around 250 hours of run time, boat engine makers recommend a change of the filter with every other oil replacement.

Key Takeaways
  • Change your boat’s engine oil at least every 100 hours but if the engine is new, change the oil every 20 hours.
  • Run the engine for a several minutes before changing the engine oil – this lowers the viscosity of the oil and suspends the contaminants.
  • Turn off the engine and replace the oil and filter.
  • Don’t spill the oil; dispose of it properly.
  • Rub a little bit of the oil on the filter gasket to help seat the oil better.
  • After changing the oil, turn on the engine and let it run for a minute or two, so the oil circulates well.
  • Look for any oil leaks while the engine runs.
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How Often Should You Change the Oil in Your Boat’s Engine FAQ

1. How frequently do I need to change the engine oil?

That largely depends on how you’re using the boat.

 If you’re using it for fun sailing once in a while, then once per year is okay but if you’re using it commercially or very frequently, then you need to change the oil more often, perhaps three or four times every year. 

2. Why do I need to change the boat engine oil?

You might have noticed that new engine oil is clear, but when it is used, it is black. The reason is, as the oil circulates in the engine, wear particles as well as carbon collect in the oil, turning its color black.

These particles are waste, and if left in the engine, they will only ruin it. Changing the oil also helps you gather how the engine is working without having to disassemble it. 

3. Do I have to change the boat engine oil filter when changing the oil?

Yes, changing the oil filter is very important when changing the oil.

That’s because there is normally some waste collected in there, and if the filter is not changed, then, the waste will continue circulating in the engine even after the oil is changed.

4. How long does outboard oil last?

4 to 5 years

How Often Should You Change the Oil in Your Boat’s Engine Final ThoughtsYour boat’s engine is its heart, and therefore its maintenance shouldn’t be taken lightly. By changing boats oil from time to time, you safeguard the vital parts from getting damaged by the contaminants in the old oil.

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That not only helps the engine run smoother but also boosts its life and leads it to become more reliable.

Read our guide on how much a pontoon boat engine cost if you ever need to buy a new one.

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