Best Boat Marine Engine Labrication Oils (2-Stroke, 4-Stroke) for Outboard, Sterndrive and Inboard Motors

Posted by Author David Lee

How to Select a Marine Engine Lubrication Oil

Lubricating oil prevents friction from occurring in engines and reduces the heat from moving surfaces contacting one another. But choosing the correct oil can be confusing. Let’s find out how to choose the right oil for your engine.

Manufacturer Requirements

The first rule for selecting engine oil is to make sure that it meets or exceeds the engine manufacturer's recommendations. These recommendations can usually be found in the owner's manual for the engine. And if for some reason you don't have your owner's manual you can go online to the engine manufacturers' website and look up the required oil specifications there.

Viscosity or Thickness of Oils for Engines

Oils for engines vary in their viscosity or thickness. You can buy single weight oils or multi-grade oils. The best place to find out information about the recommended viscosity is once again in your owner's manual and they'll usually be a small viscosity chart like this which shows you depending on the temperature in which you operate your engine, what viscosity is right for your engine.

API Service Class

Your engine manufacturer will specify an API service class for your engine which means how the engine oil performs under certain conditions. For a gasoline engine you may have an SN requirement or for diesel you may have a CJ4 requirement. Whatever your engine requires you can find it in the owner's manual. Make sure your oil meets or exceeds that API service class.

Synthetic or Petroleum-Based

Finally while traditional oils are made from petroleum, an increasing number of oils are either partially or fully synthetic. Synthetic motor oils give you longer life and will have better lubricity than petroleum oils. But before you switch make sure that your owner's manual allows for the use of synthetic oils and also make sure that before you extend the oil change interval that your owner's manual will allows you to do that as well. It may actually require you to keep the same interval of replacement. So we recommend that you go to the people who are the true experts, the guys that built your engine. In your owner's manual or online you'll find specific recommendations for the correct oil for your engine.

How to Change the Oil in an Inboard Marine Boat Engine (Diezel or Gazoline)

Just like your car your boat engine requires regular oil changes. Most manufacturers recommend that you do that every hundred hours or once per year, whichever comes first. I like to do that in the fall so that the engine will have fresh oil in it over the winter time, internal components will be protected, and come the spring I'll be back on the water that much sooner. You won't need a ton of materials but what you will need is obviously oil of the correct grade and quantity as recommended by your engine manufacturer, a ziplock bag for an old oil filter, disposable gloves, filter wrench, new oil filter, oil absorbent sheets, and plenty of clean rags, and finally a container to store the used oil in. Before changing the oil, I'm going to start the engine and let it warm up to normal operating temperature. That ensures that any contaminants in the old oil will be held in suspension and will be pumped out when I change the oil. No matter how careful you are, there's a chance that you're going to spill some oil, so a good amount of oil-absorbent pads is a great idea. I have a manual pump built onto the side of the engine. Another option is to use an oil change pump which goes down the dipstick hole and sucks the oil out that way. Either will work but we need to keep pumping until all the oil is out of the engine. So I keep pumping until I hear gurgling and I know I can't suck any more oil out the engine. After using a filter wrench to loosen the filter, I then get a Ziploc bag and put this over the filter and continue to undo it by hand. Make sure you've got sufficient oil-absorbent pads below it. After you've removed the filter, make sure that the sealing ring comes off with it. With a bag back the right way around and the oil filter in there, I can zip that up and that will contain any spills, and now I can just dispose of that properly. Smear a little oil onto the seal on the new filter so it will make a good fit and it won't leak next time. Put a little bit in the throat, too, and it will come off easily. And it's a great idea to write the date and the amount of engine hours on the side of the filter. And we're going to screw that on. Just do it up hand tight. Just bear in mind when you're filling up the engine that we don't want to overfill the engine and that's almost as bad as having too little in the engine. After letting your oil settle for a few minutes, pull the dipstick and check the level. If it's low, may need to add a little bit more oil. After refilling with oil, I double check everything. I can then start the engine and check for leaks. So now all that's left to do is just to recycle the old oil. So there you have it. It took me about an hour to do. The engine will be protected during the winter months, and come the spring, that will be one less thing to worry about. is a source where the post Marine 4/2 Stroke Engine Oils appeared first.

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Comments to Review

  1. Sierra International 18-9400-4 25W-40 FC-W 4-Stroke Marine Stern Drive Oil is universal oil, excellent low temperature operating properties and recommended for use in Mercuries and OMC. Sierra oils offer strong detergency, corrosion protection and reduced wear to the internal components, anti-oxidants and anti-wear. Excellent value and reduces my costs.

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