gas in oil crankcase. How else could gas get into oil.

[walleye1]

He needs to run it like he stole it and not idle it so much.

[BQUICK]

Could be injector leaking.....

[walleye1]

He didn't give us the hours on it.

[boscoe99]

Let's make a list of things that are known to contribute to the making oil phenomenon. I will start. Add to the list if there is something I can't remember. My mind is a shell of its former self. Too much time spent on TOS.

Insufficient engine break in
Carboned up piston rings
Excessive fuel pressure
Injector leakage
Thermostat stuck open
Extensive idle RPM
Cold water operations
Over propped
Mechanical fuel pump diaphragm leak
Failed temperature sensor

[28Regulator]

Let's make a list of things that are known to contribute to the making oil phenomenon. I will start. Add to the list if there is something I can't remember. My mind is a shell of its former self. Too much time spent on TOS.

Insufficient engine break in
Carboned up piston rings
Excessive fuel pressure
Injector leakage
Thermostat stuck open
Extensive idle RPM
Cold water operations
Over propped
Mechanical fuel pump diaphragm leak
Failed temperature sensor

Great list! TOS?

Ever hear of using synthetic oil (as opposed to dino) contibuting to making oil? I'll have my own opinion on that in a few months . . . .

Sounds like the OP's issue is pretty bad, with overflow of the dipstick hole - not typical run of the mill making oil stuff that I've seen.

[fairdeal]

Checked oil 9/13 and saw it was tan in color. Thought I blew head gasket or worse. ....Changed oil.

10/ 30 Fishing trip. Checked oil and found tan color again and oil overflowed when I removed dip stick.

As 99yam40 observes, "fuel dilution" doesn't make the oil "tan" - you need water for that

how does the OP know he doesn't have a "leaking head gasket or worse" ?

[pstephens46]

We even had a “run it like you stole it”. Covered all the bases I think. We could mention the weakness of the Plasma coating.

[boscoe99]

We even had a “run it like you stole it”. Covered all the bases I think. We could mention the weakness of the Plasma coating.

Plasma is not what it used to be. I gave blood recently so they could mine some. Maybe plasma coming from bad blood is the problem. Not as sticky as it once was. I don't know.

[boscoe99]

Great list! TOS?

Ever hear of using synthetic oil (as opposed to dino) contibuting to making oil? I'll have my own opinion on that in a few months . . . .

Sounds like the OP's issue is pretty bad, with overflow of the dipstick hole - not typical run of the mill making oil stuff that I've seen.

Yes, I have heard that. There are some engine makers that specifically exclude the use of synthetic oil being used during the first X number of engine hours. They want dino oil used, just to help the rings seat to the cylinder walls.

Based on the way that I use my motors I am not a fan of synthetic oil. Just don't see the benefit. I personally would not use it is a new or freshly rebuilt motor, just to improve my odds of the motor not making oil.

TOS stands for The Other Site. Also known as THT. The Hull Truth.

[fairdeal]

There are some engine makers that specifically exclude the use of synthetic oil being used during the first X number of engine hours. They want dino oil used, just to help the rings seat to the cylinder walls.

on the other hand,

"It’s a fact: More than 70 of the top performance vehicle models roll off factory lines with Mobil 1™ advanced full synthetic motor oil inside. "

https://mobiloil.com/en/article/why-...il-1-motor-oil

(Personally, I have no opinion on the subject....)

[walleye1]

Back in the day when the f150's came out they were having problems making oil. The problem is the longer you
run them while making oil the harder it is to seat the rings. Customers don't like to have a tech tell them to run the
sheet out of it. I have seen them with over 100 hours and still making oil. I'd change oil out and put 30 wait pennzoil
straight wait, id tell the customer to put 5 hours on the engine at wot and it did the job. Now was it because of the oil or
the run time at wot?

[boscoe99]

on the other hand,

"It’s a fact: More than 70 of the top performance vehicle models roll off factory lines with Mobil 1™ advanced full synthetic motor oil inside. "

https://mobiloil.com/en/article/why-...il-1-motor-oil

(Personally, I have no opinion on the subject....)

Yes, it is a fact.

There is also the fact that automobile/truck motors run in a somewhat different fashion than do outboard motors. To 99% of the folks a piston motor is a piston motor.

Question for you Mr. Pratt. If given a brand new 4.2 liter Yamaha what oil would you use in it? How would you operate the motor for the first 10 hours of its life?

[fairdeal]

Question for you Mr. Pratt. If given a brand new 4.2 liter Yamaha what oil would you use in it? How would you operate the motor for the first 10 hours of its life?

Oil is easy;
I would not use synthetic because I feel there is no value added when changing it at 100 hours;
so any name brand oil that meets Yamaha's stated API rating

break-in procedure is a tougher question.
I have bought some piston engines new, some used - but once in my hands, always "babied".

I have yet to run anything "like I stole it" - and so far no regrets.

My F225 came to me w/ 700 hrs - so I didn't have to break it in.

I bought the Mercury "F90" brand new - and obviously did NOT follow Mercury's instructions to the letter -
that engine has never been run over 5000 rpms.
(nor "made oil")

Here is the ECM hours dump from both engines, back when I first bought YDS:





and the 2006 Mercury 90 hp EFI 4-Stroke (Mercaha) Owners Manual:

[walleye1]

The saying run it like you stole it came from yamaha after the first 10 hours of break in.

[boscoe99]

Knowing what we know about the propensity of an outboard motor to make oil, what would be the most useful recommendations that might be made? For the small percentage of the boating public that seems to have this type of an issue.

Let's hear some ideas from all.