For those who are avid enthusiasts of boating, you might already be familiar with the fact that your boat’s engine needs to have enough oil in it, or else it won’t work well while you are out there on the water. You will certainly have to make sure that your outboard motor has enough oil before you even go out on the water. But what happens if you put too much oil in it?
For 2-stroke outboard motors, nothing significant will happen aside from how the engine will end up producing more smoke than usual while the excess oil gums up the plugs. Meanwhile, it can be different for 4-stroke outboard motors because of how too much oil can actually cause the engine to seize up.
Like everything in this world, too much of a good thing can lead to something bad. And even if oil is necessary for an outboard motor to work properly, the fact is that it will still end up in bad shape if you put too much oil in it. With that out of the way, let’s talk more about what happens when you put too much oil in your boat’s motor.
Do You Need a Primer Bulb on Your Outboard?
What Happens if You Put Too Much Oil in a 2-stroke Outboard Motor?
One of the things that you should know if you are a boating enthusiast is that you should take good care of your outboard motor. Of course, the reason for doing so is to make sure that it runs well enough for a long time. But another reason for taking care of an outboard motor well enough is that it can be quite expensive to have it fixed or replaced. In that regard, making sure that your outboard motor has enough oil is one of the best ways to ensure that it runs pretty well.
At this point, you would know for certain that you would be doing a lot of damage to your outboard motor if you don’t put enough oil in it. That’s because the oil helps lubricate all of the different moving parts you can find in an outboard motor. However, did you know that you will do as much damage to your boat motor if you actually put too much oil in it?
Yes, putting too much oil in an outboard engine can end up doing a lot of damage to it as well. But it can depend on the type of outboard motor you have because there are some differences in the way they work.
For 2-stroke engines, the possibility of adding more oil than you should is something that can happen a lot of times because of how you need to mix the oil with the fuel. If you are not using pre-mixed fuel, this can be quite common, considering the possibility that mixing up the ratios can be a really easy mistake for anyone to commit.
In that regard, what happens when you put too much oil in a 2-stroke outboard motor? Well, if there is too much oil in your two-stroke outboard motor, what happens is that it will end up gumming up the plugs because of the higher consistency of oil. When that happens, the boat’s engine will produce a lot more smoke than it usually does as it burns the excess oil off.
However, in case you are wondering, this is usually more common when you are running the boat at higher speeds because it will have to burn off the excess oil faster. When you are running at lower speeds, you will be just fine as the engine probably won’t end up producing a ton of smoke. Also, there won’t be any lasting damages left off in a two-stroke outboard motor if you happen to have added more oil than you should have.
Still, you might need to be more careful when adding oil into your outboard motor because the smoke produced by the 2-stroke engine may still end up causing a bit of damage. It would be better to be on the safe side by making sure that you don’t add too much oil.
In most cases, the best ratio in larger 2-stroke outboard motors is 50:1. Smaller outboard motors may do well with a 25:1 ratio. Also, it would be better to use the oil of the company that manufactured the outboard motor. For example, if you have a Yamaha motor, make sure to use Yamaha oils for the motor.
There are also pre-mixed fuels that you can use instead of actually mixing the oil and the fuel manually. This eliminates the chances of adding too much oil into the fuel mixture as the fuel you are using already has the right fuel to oil ratio.
What Happens if You Put Too Much Oil in a 4-stroke Outboard Motor?
While we did discuss that 2-stroke motors are more or less safe when you add too much oil to the outboard motor, the same could not be said when it comes to 4-stroke outboard motors. This is where the saying “too much of a good thing can be bad” applies as adding too much oil in a 4-stroke outboard motor can cause just as much damage as not putting enough oil in it.
Too much oil can damage 4-stroke boat motors because there is a separate reservoir where you put the oil in. That means that there is a chance that the oil may end up overflowing from the reservoir and get into the other moving parts of the 4-stroke outboard motor. This is something that commonly happens in cars but can happen in boat motors as well.
When there is too much oil in the reservoir, and it happens to overflow, it can get into the other parts of the outboard motor, such as the cylinders. The motor can actually seize up because of this, as the pistons will try to compress the oil when it should only be compressing air.
Meanwhile, another issue that can arise is when the different moving parts in the outboard motor end up splashing the oil and essentially whipping it if there is too much oil in the reservoir. When those moving parts whip the oil, this can change its consistency and make it thick and frothy. Oil that is too thick and frothy won’t be able to properly lubricate the moving parts of the 4-stroke outboard motor and, therefore, cause damage similar to when you didn’t add enough oil in the reservoir.
In summary, it can be dangerous to add too much oil to a 4-stroke outboard motor, especially when it begins to overflow from the oil reservoir. To be on the safe side, it is best to make sure that you are only adding the right amount of oil. You can even add a bit less than what you should be adding because there are some cases when the engine itself tends to “make its own oil”, which happens when the gas is blowing by the pistons.
Is it OK to Slightly Overfill Outboard Engine Oil?
We have talked about how overfilling an outboard motor can cause damage depending on what your motor is. But what happens if you just slightly overfill it? As we have talked about, it really depends on whether or not you are using a 2-stroke engine or a 4-stroke engine.
For 2-stroke engines, there really is no cause of concern here because all you will have are gunky or gummy plugs that actually won’t do any damage. It might be somewhat annoying for you to clean up the plugs, but it might even be better to slightly overfill a 2-stroke outboard motor just to make sure that it has enough oil.
Meanwhile, the same could not be said when it comes to a 4-stroke outboard motor because of how slightly overfilling it can still cause the issues mentioned above. Instead, the better decision on your part is to actually slightly underfill your 4-stroke engine because of how the engine itself can “make its own oil”.
How Do I Know if I Overfilled My Oil?
So, now that you know what happens if you overfilled your outboard motor with oil, you might be wondering how you would actually know if you overfilled it. Again, the answer here depends on the type of motor you are using.
It would be difficult to tell if you overfilled your 2-stroke outboard motor because you have to mix the oil with the fuel. The only way for you to tell if there is too much oil is when it actually begins to produce more smoke than it usually does or when the plugs gum up. Aside from that, it might be impossible to tell if you overfilled it.
Meanwhile, it will be easier to tell if you overfilled your 4-stroke outboard motor with oil because there is actually a separate reservoir where you can see the oil level. If it has gone over the full mark on the oil level, then you obviously added too much oil.
Alternatively, you can have the fuel for both of your 2-stroke and 4-stroke outboard motors tested by an expert so that you can see the fuel to oil ratio in the engine. This is by far the most precise way for you to know if you overfilled your outboard motor with oil, but it probably won’t be the easiest because you have to have someone check the motor for you.