4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (2023)

AuthorTheme: 4-Stroke Engines: "Oil Making"
Jim4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (1)Published 2003-03-23 ​​at 11:30 PM ET (US) Apparently certain 4-stroke engines like the Yamaha/Mercury 90-HP are gaining a reputation for "doing oil".

The term refers to the situation where the oil level in the lubricating oil sump rises over time as a result of contamination with gasoline that has leaked from the piston rings of the cylinders.

It appears that this problem is most evident on a new engine during the break-in period and on engines running at low temperatures, preventing the contaminated oil from boiling the gasoline.

Was this an issue on any of the 4 strokes belonging to our Whaler audience?

fat fish4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (4)posted on 2003-03-24 at 9:55 am ET (US) No!

You will smell the gas if you are in the oil smelling the dipstick. In order for the gas to pass through the rings, a few things need to happen. First, the rings are worn, but usually this will cause it to smoke. Second, a (leaking) carburetor or injector is bad, causing the cylinders to fill with gasoline when the engine is turned off and slowly passing through the rings over time. Rings are designed to contain oil, not gas. If the engine is started while this gas is in the cylinders, the compression could cause the rings to break on start up. Or a bad intake manifold gasket, etc. Gasoline entering the crankcase doesn't just "happen".

TOM4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (7)Posted On 3/24/2003 1:19 PM ET (US) Jim

After reading this post last night, I wrote to one of my friends who practices in Alaska. Your welded aluminum fishing boat is powered by a 75 HP 4-stroke Mercury engine. Because he uses the boat for both business (traveling to see patients in his locum tenens settlement) and leisure (fishing and tourism), he has logged over 300 hours on the engine in just over a year.

He reports NO [emphasis his] engine problems. He says he will be contacting the owner of some of the local fishing lodges, all of which are converting or have been converted to four-stroke engines.

Has a similar situation been described with four-stroke automobile or aircraft engines operating in cold climates? Would this situation be unique to gasoline engines, or would diesel engines be affected as well?

My technical knowledge in this field is limited, but it seems that only a malfunction would create the situation you describe.


weekend warrior4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (9)Posted on 2003-03-24 at 4:55 pm. ET (USA) I was talking to the mechanic at the local dealership the other day about a somewhat related topic and he mentioned engines that make oil. He mentioned to me that he sees this a lot on engines that have not been seated properly (rings not seated properly). I've also heard this happen on engines that are used at low speeds and don't reach their maximum operating temperature for extended periods of time. Also, I've seen this mentioned in Haynes and Clymer car manuals, commenting that this can be a problem on cars that are mainly driven at low speeds and/or on very short trips around town. In this case, it is also recommended to change the oil more often.
dgp4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (12)Posted on 2003-03-24 at 18:34 m. ET (USA) Jimh, is this just "dock talk" or do you have a resource for documented information?
Many factors come into play here; oil level at drain interval, oil mark, fuel consumed, operating hours and engine angle during check.
You are definitely not trolling here!
TOM4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (15)Posted on 3/24/2003 at 6:53 PM. ET (USA) Jim

dgp raises an interesting point. Lhg got you into this? IT'S A JOKE! Your recent posts seem to be critical of the horsepower of four-stroke engines and clearly express your loyalty to the Mercury brand.


Jim4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (17)Posted on 3/24/2003 at 9:58 PM Eastern Time (US) No, no trolling or ulterior motives. I was reading some conversations online about this.

On the Yamaha/Mercury angle, I found it amusing that the original complaint I read about this referred to the engine as a Mercury 4-stroke. But the problem is in the head.
and this is from Yamaha!

When people talk about how good their Mercury 4-stroke engine is, "Oh yeah, but that's a Yamaha engine" always comes up. So when there's a problem, he goes back to being a "Merc".

From the results seen so far, it does not appear that this is a widespread problem.

Honda outboards were also mentioned in this context.

The usual solution suggested by dealers is to change the thermostat to a higher temperature, causing the engine to run hotter. I find it helps to boil water or fuel in the lube oil reservoir.

Another review I read mentions changing the crankcase oil more often, every 50 hours. I think some people really enjoy working on their engines.

suburban boy4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (20)Posted on 3/24/2003 11:54 PM ET (USA) As hard as it is to believe, he had a fuel-injected 1,000cc two-cylinder Suzuki TL1000 motorcycle. It was not programmed correctly (routine ECU fault) and was rapidly diluting oil with gasoline. It would only take about 75 to 150 miles. The bike was removed and the ECU was changed. This eliminated the mini refinery in the crankcase. This was a well-documented fault of this Suzuki model.


gss0364-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (23)Published 2003-03-25 at 12:49 pm ET (US) I had this problem with my Honda 15 HP, (doing oil). I went to the dealer and he said the same thing as before, selling me a brand new (stainless steel?) thermostat for $75.00 which only lasted about 3 weeks (it was left open) and I really pressed him to make sure. Anyway, the new thermostat seems to work fine and not too badly. I use my Honda as a trolling motor it runs at low speed for hours like 6 hours today.
Yamaha has a really serious gas-in-oil problem on the previous model (89-90) 9.9 hp high thrust 4-stroke. I've had 3 or 4 friends who have received changes when theirs stuck due to high gas content in the oil.
I change my oil every 25-30 hours just in case, $1.29 for a quart of oil every month is cheap insurance for a $2800.00 engine.
capital4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (26)Published 2003-03-25 at 1:23 am ET (US) I've heard of many BIG engines that produce oil, like the 1271 after thousands of hours and the like, but I'm interested to know that this is a problem with the smaller 4 strokes. I'm surprised there isn't a sensor to detect this. I think this is another reason for DFI 2 hits (not for trolling). Also in a week at the height of summer I will have 30+ hours on my engines.
PECESNFF4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (29)posted on 2003-03-25 at 02:24 am Eastern Time (US) Hi Jimh,
I think you spoke to the WHO people. I personally know a gut with a twin 90 (2001) in an outrage 22 with this problem, and another with a twin 75 (2000) in an outrage 21 1970. Both were taken care of under warranty. They were less than 2 years old but had almost 1000 hours on them so Merc must know they have a problem. If I remember correctly, they said it was water in the crankcase, not gasoline. The transoms of these two boats sit low in the water and both drag slowly or drift. I only have a few hundred hours on my 90, and mine seems to burn a little oil, not gain. I get blue smoke on startup or after sitting in water for a while. The dealership said this is normal.


PFSQUAN4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (32)posted on 2003-03-25 at 08:48 ET (USA) Captain Bone - Your reference to hearing about oil production from 1271 is interesting. I used to drive a boat with Detroit Diesel 6V92 TAs, which are turbocharged engines. I had a rear engine seal leak that caused engine oil to leak into the transmission and level up. We could tell because a reverse gear has no combustion by-products. Therefore, gear oil should retain its golden color unless contaminated by water, metal, etc. However, if fuel oil gets into the engine oil, and this can happen if there is a leak in the metal jumper lines (internal fuel lines), a fire can occur. It can occur when this mixture of fuel and oil passes through the turbocharger. It happens very quickly, even before you notice a drop in oil pressure or the oil pressure alarm sounds. This happened to me one spring when I was bringing the boat back from Florida.

I'm not sure if you mean a 12V71 turbo, but in any case if fuel gets into the lube oil you have a problem.

capital4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (35)Posted On 3/25/2003 5:58 PM ET (US) I'm a big diesel fan. Everything from the 471 DD, 453, 671, 871, 892, 1271 and 1671, and the 16v149. I've always tried to play with them and learn as much as I can. They are all big movers. If you buy an old food, you can buy it for a few cents. Old turbos are the funniest things. They are as big as a 90hp outboard and in order for it to fit well you must co2 a piece to freeze it and heat the flange it attaches to for a good fit. I had an old 671 that ran away because the sleeves came loose and fuel got into the oil, when I tried to slow down the engine ran away because it pulled the oil/diesel off the crankshaft and it started to burn. He went from 2100 to set the tachometer to 4000. The boat is at 18 knots tops and that day I hit 27 knots. I took it off and nothing. So I went up on deck and used a CO2 extinguisher on the air intake to kill it. I thought I was going to fly through the roof, it was SO strong. On another occasion I hit a stump at idle and sent the 871 running backwards.
TOM4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (38)Posted on 2003-03-26 at 1:09 am Eastern Time (US) You inspired my confidence in Detroit Diesel.


capital4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (40)Posted on 3/26/2003 2:24 PM ET (US) These engines he's spent his life on are all older than I am and have had a good 6,000-10,000 hours. So they just rebuild and it still works. They are wonders, I look at the new Yanmar and river. It's a good engine, but that's not why you use Detriots. Also the new John Deeres are amazing. They are the only engines other than the DD that I would use for commercial use.
doctor t4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (43)Posted on 2003-01-04 3:29 PM ET (USA) When I was fishing in Alaska last summer, the guide mentioned that he had this problem at 40hp. Yamahas that were used in drift fishing. He said they fixed the problem by changing the thermostats.
sal dimercurio4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (46)Posted on 2003-04-28 at 8:01 pm. ET (USA) Jim, I would appreciate it if you could point me in the direction you found this information, as my friend could use a backup in other cases.
Jim4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (49)Posted on 2003-04-30 at 6:23 pm. ET (USA) Barcos rec.USENET.

The current thread here contains more information than what I first read.

David Jenkins4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (52)Posted on 5/16/2003 3:02 PM. ET (USA) If you were concerned about the build oil in your 4-stroke engine, what weight of oil would you use? I didn't get my engine manual, but the mechanic who installed it said to use Castrol 20-50. It sounds good?
blue corridor4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (55)Published 2003-08-23 at 11:37 am ET (US) Jim, the following links are recent discussions of Yamaha's F115 4-stroke oil manufacturing.





Clark Roberts4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (58)Posted on 8/24/2003 at 7:34 AM Eastern Time (US) Jenkins, correct viscosity is important for engine performance and life and I suggest you contact the manufacturer... 20W-50W seems too heavy (thick) to me, but what do I know? Mercury recommends HD 10W-30W for my 115 EFI 4 stroke. Happy Whale... Clark... Spruce Creek Marine
jws4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (61)Posted On 8/24/2003 2:02 PM ET (US) I have had personal experience with the "making oil" scenario. Yes, flowing oil fights the dipstick. 50 HP Honda I bought it new, followed the break-in procedures exactly, used specified oils and lubricants, and always over-maintained the engine. I rarely do "short runs". The typical run was yesterday about 15 miles one way nonstop at 4000 rpm and an average speed of 17.5 MPH recorded with GPS. I installed two new thermostats not because of the "oil making" situation, but simply as preventative maintenance for a saltwater engine. Also, I never failed to wash the engine with clean water on the same day it was used.

The engine produced oil when it was briefly out of warranty. The local dealer I bought it from claimed to be completely unaware of the problem. I removed the intake manifold with all three carbs and checked everything. The engine continues to produce oil. Then I replaced the fuel pump. $80 or more. Problem solved. Earlier this year, on another forum, I found a thread about how to produce oil. Poster had the same engine with the same problem as mine with the same cure.

I advise an oil analysis if you have a 4 stroke and are in doubt.

I also have a Detroit 4-53 powerboat. Sturdy little motor that will make your jaw drop if you don't have great soundproofing. Fun to work with, simple, reliable, cheap to operate and parts. "Runaway" stories are some of the best.

jws4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (64)Posted on 8/24/2003 at 2:10 PM ET (US) Captain Bone. I love those Detroits too. Interesting about 2 strokes running back. Mercury actually made a "fully inverted" outboard. To go in reverse, the engine actually ran backwards! I have a friend who was into dirt bikes. I was testing a big 2-stroke single. Unbeknownst to him, he backed up at the start and was running backwards. He accelerated and fired, going backwards! A surprise.

I apologize to the moderator. You may need a new strand in two strokes running backwards.

mrpike174-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (67)Posted on 5/2/2005 at 9:31 PM. ET (USA) I have a 2003 Yamaha F115 four-stroke that has a bad habit of raising the oil level after it has been running for a while. I also heard that another 2003 Yamaha F115 did the same thing. On my outboard the top cylinder spark plug fails when it is cold. The other did the same. I didn't think this would happen on a fuel injected four stroke engine. Is there a cure? It gets used on shorter trips so I switched to Amsoil Synthetic 4-Stroke Outboard Oil and when I changed it I purposely filled it with 1/2 liter low. After running it for a full day of fishing, I was at my peak! This actually happens and my dealer says it's fuel. No gas smell inside.
Jim4-Stroke Engines: "Oil Manufacturing" - Moderated Discussion Areas (70)Posted on 5/3/2005 1:38 AM ET (US) [This two year old thread has been revived to add a comment.]

If you have a question about four-strokes that "make oil", start a new discussion. Thanks.

[Topic closed.]

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