How Often To Change Your Boat Engine Oil (The Correct Answer)

The most important component of your boat is without question the engine. Without it, your boat is just a hull. This is why it is extremely important to maintain it properly, and that includes keeping up with the oil changes. How often to replace is a common question among new boaters. 

So how often to change boat engine oil? Most boat manufacturers recommend performing an oil change every 100 hours or once a year, whichever happened first.

You should always check your engine’s owner’s manual for a more specific interval between oil changes. 

There are other things to take into consideration when trying to determine when to do your next oil change. We are going to explain all of them in this article.

Type of engine 

Even though all boats don’t have the same kind of engine, all of them require good oil to run smoothly. Whether you have an outboard, inboard, jet drive, or a diesel engine, the manufacturer’s recommendation it’s mostly the same every 100 hours or once a year.

There are some instances where this recommendation might be different, for example, new and old engines. 

New engines- on new boat engines, during the “brake-in phase,” it is recommended to perform oil change after the first 20 hours. After that, switch to 100 hours or once a year, whichever comes first. 

Old engines- Continue replacing the oil every 100 hours or once a year on boat engines with high hours. The number of hours or intervals between oil changes doesn’t change on a high hour engine. But keep in mind that as the engine ages, it becomes more critical to keep up with oil changes. Having fresh oil running trough your boat engine will prolong its life.

How important is changing the oil on your boat’s engine

Oil is a vital part of your boat engine, it is in charge of keeping all the moving parts inside the engine running smooth. Over time, oil breaks down and gets contaminated with 

Proactively changing a boat engine’s oil and the filter will help the engine perform at it’s best and also prevent expensive repairs in the long run. The average cost of an oil change for a single-engine is about $75.00 if you do it yourself or $300.00 if you take it to the shop. Now compare that price to the possible cost (could be thousands) of having to repair the engine if not appropriately maintained. This is why it is essential to change the oil on your boat’s engine. If that is not enough, Hera are other good reasons to consider

  • Promote fuel economy- Routine oil changes will help keep your engine properly lubricated and clean. This means less unnecessary friction, which results in better gas millage. A poor maintain engine will have to work harder, resulting in poor fuel consumption.
  • Maintains a clean engine- Over time, the oil in your engine will contaminate with metal particles, dust, and dirt. Changing the oil and filter on the schedule will get all that unwanted stuff out before they can do any damage to the engine. It will also prevent broken down oil from turning into slush.
  • Keep engine components cool- Routinely oil change will ensure proper lubrication to all the moving parts inside your boat’s engine. Proper lubrication means less friction, which means less heat. Keeping the parts lubricated and cool is vital to the health of the engine. 
  • Will make your engine last longer- Proper lubrication will make your engine run smoother, an engine that has to work harder because of inadequate lubrication will brake down well before a properly lubricated engine. 
  • Better engine performance- One of the effects of oil breaking down is that it will lose its viscosity, and slush will start to build up. It is like having an engine with hi cholesterol, it will get harder for the oil to go where it needs to go. The engine will have to work harder to move the oil and keep its parts lubricated; this will reduce gas mileage and overall performance.
  • Protect the engine- Marine 4 stroke engines run cooler than automotive 4 stroke engines. The accumulation of moisture combined with the contamination on the oil will turn the oil acidic. You don’t want this acidic oil sitting at the bottom of the engine. This acidic oil can rust internal parts of the engine creating big problems and costly repairs. 

What happens if I skip an oil change

You might get lucky, and nothing will happen if you skip an oil change. But the reality is that without opening the engine, it will be impossible to know if by skipping an oil change, you might have caused some kind of damage.

More than likely, every time you skip an oil change, some wear and slush formation happen. The best way to prevent this is by changing the oil regularly. 

So it might not be noticeable at first, but skipping oil changes can be fatal for a boat’s engine.

If you have skipped oil changes, it is a good idea to take your boat to the shop and explain what happens. They should be able to run some tests and determine if any damage has occurred and helped you determine the best way of fixing the problem.

DIY vs. Taking It To The Shop

There is no right or wrong answer here, the reality is that you have to do whatever is convenient for you and fits your lifestyle. I like to work on my boat and have chosen the DIY method, here I’m going to give you the reasons why

  • It is easy- If you are mechanically oriented or can follow a YouTube, you can do your own oil change on your boat’s engine without any issues. It will take you less than an hour and only require a few tools. 
  • It is cheaper- The cost of the DIY method for a single-engine will range between $75.00 to $100.00 for the oil and filter. The cost of taking it to the shop will vary from $250.00 to $300.00 for a single-engine. Owning and maintaining a boat can be pricey, and very little saving helps.
  • It faster- With the DIY method, there is no need for appointments, towing your boat to the shop, and having to wait for it for a couple of days and sometimes weeks. You can do it on your own schedule, and it will only take about an hour.
  • I know it’s done right- Nobody is going to take care of your stuff better than you. Sometimes boat shops get busy, and the employees can make mistakes and put the wrong oil in. I had this happen to me once.
  • Chance to inspect other components- Doing your oil change will give you the opportunity to examine other parts of your boat. While you wait for the pump to get the oil out, look around and make sure everything looks the way it’s supposed to look. If anything looks suspicious, you can inspect it closer and repair if necessary 

Will doing My Own Service void the warranty?

DIY your boat’s engine oil change will not void the warranty. What will void your warranty is not servicing your boat according to the manufacturer’s recommendations.

The important thing to keep in mind is evidence. You will need some evidence that the required maintenance has been done. Keep oil and filter receipts and a log with date and hours when the service was done.

Related Questions

How often should I change lower unit oil? Both outboard and sterndrive manufacturers recommend replacing the lower unit oil every 100 hours or once a year whatever happens first.

What tools do I need to change the oil on my boat?

Alejandro Cruz

I’m part of a family of "aquaholics" We love everything about the boating lifestyle. From fishing to exploring new waters to everything in between. We love going on new adventures as well as just chilling in the water. In this website, we want to share with you everything we have and continue to learn about the boating life 365!!

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