Outboard Lower Unit Oil Changes: What You Need, How to Do It, How Often, and What It Costs

Outboard Lower Unit Oil Changes: What You Need, How to Do It, How Often, and What It Costs

If you want your boat to last, regular maintenance is essential, and one of those tasks you can't ignore is changing your outboard lower unit oil regularly. Without this task taken care of, the gears can become damaged due to the heavy loads they handle. While you can trust a boat mechanic with this process if you want, it's also simple to do so on your own.

Why You Need to Change the Oil

While it isn't too difficult to handle your own lower unit oil change, you do need to have the right equipment on hand. At a minimum, you'll need:

●       New lower unit oil

●       Drain pan

●       Lower unit oil pump

●       Replacement sealing washers and O-rings for vent plug and drain screws

●       Large, flat-head screwdriver

●       Disposable gloves

To help clean up any potential spills, you should also keep several clean rags nearby. It's also helpful to have a container at hand that you can use to store the used oil in to dispose of later. You can recycle your used oil at a hazmat recycling center.

When picking out the fresh oil to use in your replacement, make sure that the type matches with the engine manufacturer's recommendation. This way, you'll have the best fit for your outboard lower unit without any potential complications in the future.

How Often Should You Change Your Outboard Lower Unit Oil?

Changing your oil is a type of preventative maintenance that will help keep your outboard lower unit in prime shape, so long as you keep up with it. At the bare minimum, you should change the oil out at least once a year, and that can be enough for people who only occasionally use their boats.

However, the more you take your boat onto the water, the more work the engine goes through, which can increase the need for oil changes. Much like how cars should receive an oil change every thirty-thousand miles, your outboard lower unit oil requires changing every one-hundred hours the boat is in operating.

Without regular lower unit oil changes, you run the risk of damage occurring in the engine. Usually, repairing these sorts of issues is expensive, and it's worth the smaller investment of your time and money to tend to your oil changes as recommended.

Changing the Oil

The process of changing your oil is relatively simple. Having your catch pan in place beneath the drain, you want to use the screwdriver to remove the lower drain plug. This stage can be somewhat tricky if the housing has become corroded. Additionally, you should be careful to keep the screw from falling into your catch pan to save you from cleaning it up afterward.

Next, remove the upper vent plug screw of the lower unit. Afterward, you'll need to wait until the oil has drained; this process can potentially take up to an hour, so be sure to give it plenty of time to finish.

With all old oil drained, you can now connect the pump adapter to the lower drain hole and your bottle of oil and start to fill the lower unit. You'll be able to tell that it's become full when you start to see oil dribble out of the upper vent plug hole.

When reassembling the parts, you can install your new O-rings and sealing washers and clean up any debris or mess. As you return the screws, start with the upper vent plug, then move to the lower drain hole. You should keep the screw close as you remove the pump adapter to prevent more oil than necessary from spilling out.

To wrap up the process, use your rags to clean up any stray oil and place your used oil in a container for safe recycling.

Keeping an Eye on Your Oil

Aside from being helpful for your boat, an oil change is an excellent time to look for signs of potential problems. Large metal chunks in the oil (as opposed to little metal fillings), or oil discolored to be gray or white color can all indicate more significant issues that can cause your boat trouble. If you see these signs during a DIY job, then it's time to consult a mechanic.

Oil Brand Options and Cost

Just like with other types of oil, you'll find that you have several brands available to consider. If you're worried about picking the right kind or you feel unsure figuring out which is the best for your boat, going with the manufacturer's recommendation is the safest choice.

However, for the most part, you should be able to use any lower unit oil without worrying about damaging your boat, so long as it's suitable for marine use. If you want to get an idea of how much it will cost you, here are the prices of some popular brands:

●       Mercury - $23.81 - $29.99

●       Yamaha - $19.17

●       Quicksilver - $17.08

●       Johnson - $15.43

●       Lucas - $29.10

When shopping for a ship, it can be easy to get caught up in new boat prices and forget about maintenance costs. While a necessary component of taking care of your vessel, lower unit oil changes are a relatively inexpensive form of caring for your boat that can easily prevent other, costlier issues. Even so, you should still account for oil changes in your boating budget.

Again, the critical aspect is that the oil is suitable for marine use, regardless of which brand makes it. If you use a lubricant meant for an automobile, you can potentially risk damaging your engine or voiding your warranty for not using the appropriate oil.

If you don't yet have a lower unit oil pump, prices for these tend to fall under twenty dollars on average, and you can easily find cheaper when looking for them. You can also find a set of marine drain screw gaskets for under ten dollars without any trouble.

The cost of having a mechanic handle your lower unit oil change will entirely depend on the listed labor costs for the job—sailboat prices and power boat prices for the same job won't differ much. However, in most cases, it's much easier and more cost-effective to handle the change yourself.