Making oil?

[tmusky1]

2002 Mercury 90ELPT Serial #0T562954
I've seen a couple posts regarding these 4 strokes "making oil" and the general understanding is gasoline is getting past the piston rings into the crankcase.
The advice I've seen is to drain the oil to the recommended level.
That doesn't seem like a very good fix,as the oil is still contaminated, even an oil change is a waste of money and time because the first time you run it, the gas is going to contaminate the oil.
So what's the proper way to fix the problem? Could a simple valve adjustment do it? I'd rather not re-ring my pistons but it's hard to believe it's "normal" for any 4 stroke engine to "make oil"

[joe3buck3]

I am not sure what the ultimate fix is but a friend and I had identical 60HP mercury 4strokes. Initially his made oil while mine did not. I concluded that the probable difference was I used my boat on a large lake while his was restricted to a small private lake. I routinely ran my engine WOT several times during my outings and he almost never got to WOT. I surmised that my engine heated up enough to boil away any gas while his did not and it accumulated over the course of several months. His solution was to change his oil more oftern. His engine stopped making oil after it had accumulated over 100hours. I have read other accounts where these engines seem to stop 'making oil' after accumulating some hours.

[Nova Kaw 650]

2002 Mercury 90ELPT Serial #0T562954
I've seen a couple posts regarding these 4 strokes "making oil" and the general understanding is gasoline is getting past the piston rings into the crankcase.
The advice I've seen is to drain the oil to the recommended level.
That doesn't seem like a very good fix,as the oil is still contaminated, even an oil change is a waste of money and time because the first time you run it, the gas is going to contaminate the oil.
So what's the proper way to fix the problem? Could a simple valve adjustment do it? I'd rather not re-ring my pistons but it's hard to believe it's "normal" for any 4 stroke engine to "make oil"

Has it always done this?
Keep in mind that it's now a 15 year old motor, so that could be a factor depending on the hours.
Unless the oil level is rising too quickly, I would change the oil mid-way through the season, and at the end of the season.

[tmusky1]

I've only had it a year. I had the motor checked out by a reputable Merc service tech before I bought it and compression was within spec. (100-115lbs) The guy I bought it from fished very small lakes and barely went through a tank of fuel the whole season. (These lakes are oversized ponds with one having a no wake law)
Since I've owned it, I've gone through 5 tanks of fuel with a lot of that time being at wot. Guess I'll keep monitoring it through next year and maybe look at a midseason oil change

[jethro1]

On an older motor that starts "making oil", that did not make oil in the past, then the rings and piston grooves may have an excessive amount of carbon build up. A decarboning treatment might do the trick.

Do the carbon treatment followed by a compression test. If the compression tests is within specifications the making oil problem may go away. If the compression values are substandard, particularly if air flow pass the rings is indicated, it may mean that it is time for new rings.

Any brand of four stroke motor "making oil", while maybe not normal, is not abnormal either. Many many do it. New/old does not matter.

[tmusky1]

Since I've owned it, I've added Quikleen to every tank, also added Quikcare to the last 3 tanks. Something I would bet the previous owner never did. May just be something I need to monitor while running wot and continuing with additives

[jethro1]

Yamaha dealers have access to a super concentrated chemical that is intended to decarbon a motor. I suspect that Mercury may also offer such a product, for use only by a Mercury mechanic at a Mercury dealership.

What the consumer can use for himself is like using ibupropen for pain whereas the doctor can use heroin.

[EuropeanAM]

Couple of important questions:

-What oil (specifically, including viscosity) are you running?

-WHERE on the dipstick is the oil level set at when CHANGING the oil?

-How far up the dipstick (over "X" amount of runtime) has the oil level climbed?

-Is the engine coming up to temperature, and running for at least 15 minutes above 3500 RPM's each time you're out?

[tmusky1]

Oil is Quicksilver 10w-30
Oil level was set to the full mark
Level climbed 1/8 - 3/16 above the full mark. I don't have an hour meter but I would guess less than 12 hours run time
I don't have a temp gauge but I let it warm up about 5 minutes before running.
Yes, the motor runs above 3500 rpm for over 15 minutes total but not 15 minutes straight

[Nova Kaw 650]

1/8" is REALLY hard to judge on a dipstick, especially on an outboard that tilts.

[tmusky1]

Using an electronic level, I made sure it was level each time I checked it.
(As a metal fabricator, I'm weird like that)

[Nova Kaw 650]

Using an electronic level, I made sure it was level each time I checked it.
(As a metal fabricator, I'm weird like that)

Left and right as well?

[tmusky1]

Yes, the motor was level

[EuropeanAM]

Several Recommendations:

In summer conditions, use 25W40 oil. You will HAVE to use 10W30 if you're running in the winter, based on your location.

When filling oil level, fill to 1/4 (25%) into the SAFE ZONE only. Do NOT fill to the "full" mark, as this will result in an over-full condition when hot.

It's important that the engine come up to temp, and run at 3500+ RPM's for a minimum of 10 minutes (preferably 15 minutes or more) during outings. This ensures that moisture and/or fuel that does get into the oil is evaporated.

[tmusky1]

Thanks for the advice on the oil, I'll change it out in the spring.
Are you suggesting 15 consecutive minutes? On some of the smaller lakes, that would require me to run several hot laps before I get to my destination 5 minutes down the lake.

[EuropeanAM]

It really would be best to have 15 or more consecutive minutes of running at planing RPM's.

[620Ranger]

I'll throw it out there but the real experts are going to need to chime but had a similar issue on my 2002 4 stroke 10hp kicker 2 years ago. Had to drain oil?? out after every trolling trip. It was so bad when you removed the fill plug fluid would run out it because it was so overfilled.Since it was never really used at any speed barely above idle I thought it could be a condensation issue but that would have been a lot of condensation. Talked to my local Mercury dealer and he said I probably had a bad diaphragm on my fuel pump. I said ok, sell me a diaphragm. Could not buy just the diaphragm so I had to buy the whole fuel pump. Changed it out and haven't had a problem since. Somehow the bad diaphragm was letting gas leak into the crankcase where it attached to the block. I have no idea if your motor is configured like mine or not, that's for the guys on here that know what they're doing.

[EuropeanAM]

I'll throw it out there but the real experts are going to need to chime but had a similar issue on my 2002 4 stroke 10hp kicker 2 years ago. Had to drain oil?? out after every trolling trip. It was so bad when you removed the fill plug fluid would run out it because it was so overfilled.Since it was never really used at any speed barely above idle I thought it could be a condensation issue but that would have been a lot of condensation. Talked to my local Mercury dealer and he said I probably had a bad diaphragm on my fuel pump. I said ok, sell me a diaphragm. Could not buy just the diaphragm so I had to buy the whole fuel pump. Changed it out and haven't had a problem since. Somehow the bad diaphragm was letting gas leak into the crankcase where it attached to the block. I have no idea if your motor is configured like mine or not, that's for the guys on here that know what they're doing.

This does happen occasionally... but as you indicated, it is usually a very overfull condition, with a STRONG indication of fuel-contamination (thin, fuel-smelling oil).

[Skeeterbait]

I know that during breakin on my 16 115 four stroke made oil. The oil line on the dip stick moved from middle of the hash marks to slightly above the full mark. I proceeded to release 2 liters and added back 1 fresh liter. Once thru breakin it has slowly decreased over the next 100 hours but I always check after ever trip. Once more I had to release 2 liters and add back one. It seems to have stopped now... or I am running it harder and evaping it off one or the other. This fall I will spend more time idling around and we will see if it is still doing it. But either way, not filling to the full mark to begin with, watching it after each trip, and being prepared to release 2 and add 1 back to regain some viscosity every once in a while, along with completing every recommended full oil change should maintain protection. The fact is even your truck probably allows a little fuel bypass, but it maintains high enough temp to evap it off and keep everything maintained. These outboard 4 strokes just run very cool and not everyone needs to make long runs every time they us them.