Why Change 4 Stroke Lower Unit Outboard Motor Oil?
On 4 stroke lower unit outboard engines, other than checking your oil level at regular intervals, changing the oil is the next most important task. Regular oil changes will prolong the lower unit outboard life. You can do this task yourself without too much trouble. Just remember to think in a methodical manner and have everything at hand before starting. Here are the steps you need to take to change your lower unit outboard motor's oil.
1. Always follow the lower unit outboard manufacturers recommended maintenance schedule. For example, for small outboards the oil would normally be changed every 50 hours. For large horse power lower unit outboard engines this may be every 100 hours. If you do not use the outboard very much and do not keep a record of the number of hours that it is in use, then always change the oil every year.
2. Gather around you a number of useful tools. A large screwdriver, adjustable spanner, a socket set with a box spanner, an oil filter wrench, a funnel, a bucket or some kind of container to hold the old oil, the new oil, perhaps an oil filter to replace the oil one, WD40 or similar, grease tin, a plastic bag, and some old rags.
3. Have the lower unit outboards manual by your side. Check to see how much oil the lower unit outboard takes and obviously the grade of oil. When an lower unit outboard motor is new the manufacturers like you to use a certain brand of oil, but this is not so important with older engines. As long as it is the same grade and of good quality, it will do the job just as well.
4. Before changing the oil, run the engine until it is warm. Why? Well warm oil will flow easier than cold oil! You will need to put the lower unit outboard in some water before starting or you could use engine muffs designed to allow fresh water to flow through the motor as it runs. Sometimes these muffs are called flushing devices. If you connect the system to your garden hose just make sure the tap is not fully on, adjust the flow accordingly.
5. Once the engine is warm. Take out the oil dipstick or the oil cap and put them to one side. This will help drain the oil. Unscrew the drain plug either with a spanner or screwdriver, depending on the engine. Put it to one side (in a safe place). Remember to catch all the old oil in the bucket or container.
6. Some lower unit outboard engines have an oil filter, if so, then remove this also by having a plastic bag to hold it in and put to one side. Next screw in the new filter a few turns, then using the rags clean the base (filter seat) and using some grease smear some around where the filter is going to rest in. Continue to screw the new filter in by hand until tight, then tighten an extra half turn. If your engine does not have a replacement oil filter, perhaps it is connected to the drain plug, then clean it with some petrol to remove any trace of the old oil.
7. With the drain plug firmly back in place you are ready to fill with the new oil. Use a funnel in the filler hole to avoid spillages. Fill with oil until it reaches the maximum level on the dipstick. Then replace the oil cap or dipstick.
8. Start the lower unit outboard motor and run it at idle speed for 3 minutes. This is long enough to allow all the new oil to get to every part of the engine it should reach. Check the oil pressure warning light goes off and that there are no leaks around the filter or drain plug.
9. Stop the lower unit outboard motor. Leave it for 3 minutes to allow all the oil to return to the sump. Then remove the dipstick to check the level. Top up with oil if it is necessary.
10. Finally, dispose of your old oil in accordance with your local laws. Some areas have a local dump that you can take your old oil to and they will take care of it for you.
This procedure can be messy but it is necessary. It is quite within most boaters capability to do without sending the lower unit outboard to a dealer or mechanic.
