# How often to change outboard motor oil?



## matthewwhill (Dec 10, 2012)

I have a 2012 four stroke 4hp outboard. I use it frequently - about twice a week during the winter and early spring. But only for 5-10 minutes at a time to get out of the marina. How often would you recommend changing the oil?


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## tommays (Sep 9, 2008)

With your type of use I would change it more often like every 6 weeks 

I say this because the four stroke suffers from two issues that affect the oil ,water vapor and fuel dilution 

These are less of a problem when running the motor for long amounts of time BUT at 5 to 10 minutes the oil is never going to get warm enough to cook off the water and fuel contamination


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## Minnewaska (Feb 21, 2010)

I would warm it up a bit more, let her idle while you're getting ready. 

Does your boat come out of the water at all? I change the oil in the 18hp dinghy motor at the beginning and end of each season. Yes, I change it at the beginning, even though it hasn't run since I changed it in the Fall. Engine oil has protectants that degrade just sitting there. 

I suppose it would be better to do a mid-season change too, but nearly impossible, without hauling the dinghy.

Search online for the operators manual, if you don't have it. They will be fairly specific about time and hours between changes.


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## Alex W (Nov 1, 2012)

The manufacturer of your motor should tell you. They probably say every 50 or 100 hours.

The motor on the Catalina 25 that I sail is used similarly. The oil on it has been changed every 6 months, and gear oil once per year. We do the oil changes while the boat (and engine) are in the water by sucking oil out of the dipstick, but do the gear oil when the boat is hauled. Since your 4hp motor is a lot lighter than this 9.8 I would just remove the motor from the boat to do the service.


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## zz4gta (Aug 15, 2007)

Any good online how to sites that cover this? I'm very familiar with automotive engines, but haven't done lower unite or marine engine maintenance often.


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## Minnewaska (Feb 21, 2010)

zz4gta said:


> Any good online how to sites that cover this? I'm very familiar with automotive engines, but haven't done lower unite or marine engine maintenance often.


YouTube has several. If a homemade vid, you have to take any advice with a grain of salt, but it take the mystery out of doing it yourself, if you watch someone else do it on a vid first.


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## Alex W (Nov 1, 2012)

The manual for your engine will show you where the oil pan screw is. Changing the oil is just like a car, warm up the engine (if you are on the hard then put it in water to get cooling water through the engine), remove that screw, and collect the oil. When I'm doing this on the water I suck the oil out of the dipstick (just like one would do on an inboard engine) to avoid mess. On my two engines (Honda BF2 (2hp dinghy engine) and Tohatsu/Nissan 9.8) there is no oil filter. Both are 4 stroke.

To change the lower gear oil you remove two bolts, one above and one below the gear box. This will also be shown in your engine's manual. Once all of the gear oil has run out you use a pump with a special threaded fitting to pump oil in through the lower bolt. Pump until oil comes out clear at the upper threaded hole. Put the upper bolt back in, remove the pump, and put the lower bolt back in. It takes about 10 minutes.

I haven't tried doing that over the water. I would only do so if you have a dinghy under the engine that is full of oil absorbent pads. Please don't let even a drop of oil get into the water.

The hardest project is replacing the water pump impeller. There are good looking instructions about halfway down this page for the Nissan/Tohatsu engines:
Association Forum - Tohatsu / Nissan 9.8 water pump replacement

I haven't had to do this.


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## CarbonSink62 (Sep 29, 2011)

I was a real newbie with OB engines at the start of last season; I bought the book (Clymer's Manual) and got my '81 Evinrude 9.9 running with the help of some folks here.

I don't expect to have much trouble doing the service on my '04 Honda (just bought it off Craig's List). These things are set up so the average joe can do the regular maintenance.

If the oil degrades in the engine, why not drain it at the end of the year and just put in new stuff in the spring?

FYI - This is my planned service schedule (please comment)

This year (because I just bought the OB):
Rebuild water pump
New oil & filter; new fuel filter; new plugs; new lower unit oil;

Every year:
New oil & filter; new fuel filter; gap the plugs; new lower unit oil;

Every other year:
Rebuild water pump
New oil & filter; new fuel filter; new plugs; new lower unit oil;

I hope to get out sailing twice week; I motor for an hour each way;

I've heard that 4 stroke sailboat auxiliaries can get water in the engine oil because they are seldom run hot enough to liberate the water vapor. I intend to run at 3/4 throttle for the last 20 minutes of the transit to my mooring. Then it will run very slow for 3-5 while maneuvering before being shutdown. That should take of the problem. (right?)

Ken


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## tommays (Sep 9, 2008)

IMHP because of the winter use and short duration of runtime the OP is operating in a severe duty cycle 

For my personal use once a year in the fall is fine


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## Minnewaska (Feb 21, 2010)

CarbonSink62 said:


> ....If the oil degrades in the engine, why not drain it at the end of the year and just put in new stuff in the spring?


Fresh oil contains some anti-corrosive properties and you wouldn't want any sludge in the pan to harden. Further, running it for a few minutes with the fresh oil, should displace all the old oil that doesnt drain from passageways. Old contaminated oil can actually do damage just sitting on engine parts all winter.


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## mad_machine (Dec 16, 2012)

not getting the engine up to temp is the worst thing you can do to an engine. The oil never warms up to properly coat all the internal friction surfaces, it never cooks off the water and fuel contamination, and the water vapor in the exhaust never gets burned off/out so it causes corrosion in the entire exhaust system. If you don't need to run it much to get in and out of the marina, consider once a week or so just running it (in gear under a load) for 20 minutes or so just to get it up to a really hot temp.

The wasted fuel is cheaper than a rebuild


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