How to Change Mercury Outboard Engine Oil and Gearcase Lube

May. 1 2023 News By Mellissa F.

At Boater’s World, we know how important it is to keep your boat's outboard engine running smoothly. That's why we've created a playlist of videos dedicated to Mercury outboard engine oil and gearcase lube changes. In this article, we'll go through each video, step-by-step, so you can learn how to change the oil and gearcase lube in your Mercury outboard engine.

Mercury 20 Outboard Oil Change

The first video in our playlist shows how to change the oil in a Mercury 20HP 4-stroke outboard motor. You should change the oil in a Mercury 20HP 4-stroke motor after every 100 hours of run time. The video starts by lifting the motor up to drain out the old oil, twice. Next, we remove the old oil filter and replace it with a new Mercury outboard oil filter. Finally, we refill the engine with 1.1 quarts of fresh Mercury oil.

Mercury 25 Outboard Lower Unit Oil Change

The next video in our playlist shows how to change the lower unit oil (gearcase lube) in a Mercury Tracker 25 outboard. We start by removing the vent and drain plugs and using a Mercury gear lube pump to fill the gearcase with fresh lower unit oil. When you see gearcase oil running out of the vent opening at the top, you know it’s full.

Mercury 40 Outboard Oil Change

In this video, we demonstrate how to change the engine oil in a Mercury 40 HP 4-stroke outboard. We show how to remove the cowling, locate the oil drain bolt, and get the old oil drained out. Next, you’ll see how to replace the drain bolt and the oil filter, and refill the outboard engine with about three quarts of 25W40 Mercury synthetic oil.

Mercury 40 Outboard Lower Unit Oil Change

If you have a Mercury 40HP outboard, this video will show you how to change the gearcase oil. We start by opening the vent bolt and the drain bolt to get the old lower unit oil out. Next, we check the lower unit for leaks in the seals at the prop shaft and drive shaft using a gearcase pressure tester. After the pressure test, we refill the lower unit with fresh gearcase lube using a hand pump specific to Mercury that fits the fill opening.

Mercury 40 Outboard Lower Unit Oil Change (Two Stroke)

If you have a Mercury 40HP two-stroke outboard, this video will show you how to change the lower unit oil. This job requires a Mercury gear lube pump with the correct fitting. We show how to drain out the lower unit oil, followed by a gearcase pressure test. After the test, we pump fresh gearcase oil into the engine before closing it up.

Mercury 115 Outboard Oil Change

The next video shows how to change the oil in a Mercury 115 outboard. We use a complete Mercury outboard oil change kit for this job, which is cheaper than buying the standard oil and oil filter individually. The oil change process for a Mercury 115 is pretty simple. First, we remove the cowling to access the motor. Then, we tilt the motor up in order to drain the oil. After draining the oil, we replace the drain plug and then the oil filter. Finally, we refill the engine with 4.8 quarts of oil.

Mercury 200 Outboard Oil Change

This video shows how to change the oil in a Mercury 200XL Verado outboard engine. You can use either synthetic oil or standard oil for this job. We demonstrate how to drain the oil, replace the oil filter, and then refill the engine with 6.3 quarts of oil and set the oil level.

Mercury 200 Lower Unit Oil Change

The final video in our playlist shows how to change the lower unit oil in a Mercury 200 outboard. Unlike many oil changes, you drain the engine oil at the bottom and fill it at the top. We show where to find the vent and drain bolts and then use a Mercury gear lube pump to force the gearcase oil into the unit from the drain opening. The lower unit is full when you see the gearcase lube running out of the vent opening at the top.