Yanmar 3gm30f oil loss

[Lepke]

Try slowing down. Your engine may burn less oil, it will for sure save fuel and extend engine life. As diesels became popular in recreational boats, the engine companies ran them at higher rpm to please owners need to go faster. When I started in boats, most diesels ran at under 1000 rpm, and many below 300 flat out. Detroit Diesel/Gray Marine were some of the first to allow cruising above 1500. And they're heavy duty, most yacht diesels are light duty.
Diesels naturally burns some oil, and at high rpm and temps, more oil. The rings are designed to carry oil to the upper cylinder/sleeve walls to lube and then scrape most oil back down. At high rpm there is more heat and clearances expand, the oil is thinner and escapes easier. As an engine ages, expect higher oil burning at high rpm.

[CapnKernel]

Originally Posted by wsmurdoch

When I read your note, I had visions of a wing walker pouring a quart of oil into the port engine of an airplane in flight at 200 kts. I'm still chuckling.

If it's mid-air oil life-and-death oil changes, read this. Your heart will be in your mouth.

Smithy's flight accross the Tasman - PPRuNe Forums

For some time I had noticed a steady stream of blue smoke in the exhaust of the port engine. It was obvious that this engine was burning oil. The outboard engines were isolated alone, far out in the airstream under the wing. I reached the alarming conclusion that the only way to do this oil transfer was to go out there and get the oil from the starboard side and go out again to put it into the tank on the port side.

I will never complain about another oil change!

[rognvald]

Originally Posted by Lepke

Try slowing down. Your engine may burn less oil, it will for sure save fuel and extend engine life. As diesels became popular in recreational boats, the engine companies ran them at higher rpm to please owners need to go faster. When I started in boats, most diesels ran at under 1000 rpm, and many below 300 flat out. Detroit Diesel/Gray Marine were some of the first to allow cruising above 1500. And they're heavy duty, most yacht diesels are light duty.
Diesels naturally burns some oil, and at high rpm and temps, more oil. The rings are designed to carry oil to the upper cylinder/sleeve walls to lube and then scrape most oil back down. At high rpm there is more heat and clearances expand, the oil is thinner and escapes easier. As an engine ages, expect higher oil burning at high rpm.

Well said, Lepke. I would like to add a couple thoughts:
1.) If you're in the Bahamas, why are you running a multi-grade oil?
The recommended oil for your engine is straight 30W. The weather
will never be cold enough to justify a multi-grade.
2.) Do you vary your RPM's every hour while motoring to avoid a "set"
in the piston/cylinder at your running speed?
3.) Do you run your engine occasionally over 2500 RPM's to "blow out"
the cylinders?
4.) Do you idle your engine to cool down after use?
5.) Do you rev your engine after cool before shutting down?
6.) Do you use a diesel conditioner and change your filters regularly?
7.) Do you pre-filter your fuel?
These ideas may or may not be contributory but are necessary to good marine diesel maintenance. However, before I incurred any major cost, I would change my oil filter and switch to RotellaT 30W and run it for 100 hours with the above recommendations and see if anything changes. Sometimes, it's the simple things that cause what appear to be major problems. I hope this helps. Good luck and safe sailing.

[four winds]

A quick correction.

Engine oil is 15w40

Gear oil is 30w, except saildrives, then 80 or 80w90.

[Catalysis]

Originally Posted by CapnKernel

If it's mid-air oil life-and-death oil changes, read this. Your heart will be in your mouth.



Smithy's flight accross the Tasman - PPRuNe Forums







I will never complain about another oil change!

Wow !

[rognvald]

Originally Posted by four winds

A quick correction.

Engine oil is 15w40

Gear oil is 30w, except saildrives, then 80 or 80w90.

Fourwinds,
My engine is a 1990 3GM30F. The Yanmar shop manual and the original Pearson manual for that year recommends straight 30W for the engine, Dextron ATF for the transmission(Kanizaki) and Texaco for the heat exchanger. This is what I have used for the last 22 years. Perhaps your above submission is for a different/later model year. However, the OP should probably check with Yanmar if there are different recommendations for different model years. But, from a purely technical/mechanical basis, a multigrade oil isn't necessary in the Tropics where the ambient temperature is usually in the seventies or well-above. There are not enough temperature variations to justify a multigrade and, the OP may find with an oil/filter change with a straight grade oil, he may have less oil consumption. This is certainly a less expensive alternative than an engine rebuild or a call from the mechanic. Good luck and safe sailing.

[Cheechako]

My 3GM30's were 1992. I was surprised but the manual recommended 30 w engine oil in the Kanzaki transmissions.
Multigrade oils are by and far the recommended type in most modern engines and climates because most engine wear occurs when the engine is first started.... than after it has warmed up.
Whether you are in Baja or Canada is irrelevant, the engine runs much hotter internally than the climate anyway.

[rognvald]

"Multigrade oils are by and far the recommended type in most modern engines and climates because most engine wear occurs when the engine is first started..." Cheech



This is absolutely correct and IS the reason for the multi-grade oils in colder climates where excessive engine turning without starting will damage your engine. However, in the Tropics, this is never the case and the reason for a multi-grade oil is moot, at best. I believe there is no real superiority of a multi-grade oil vs. modern straight grades(Rotella T) unless "cold starting" is involved and the reason it is now recommended by manufacturers is to ensure that unknowing boat owners do not cause premature wearing of the cylinders/pistons in colder climates or through, even, a general lack of regular oil maintenance. Again, Yanmar may be the best resource for determining the oil recommended for YOUR engine. Good luck and safe sailing.

[four winds]

It's my understanding that Yanmar changed the recommended oil to multi grade for all 3gm30f engines. The newer manuals reflect this, starting sometime around mid to late 1990's.

[rognvald]

Originally Posted by four winds

It's my understanding that Yanmar changed the recommended oil to multi grade for all 3gm30f engines. The newer manuals reflect this, starting sometime around mid to late 1990's.

For the sake of an academic argument, what is the purpose of a multigrade oil when used in a climate where the ambient temperature is rarely below 60 degrees? Multigrade oils were developed by the oil industry for engines that were used in a wide range of temperature conditions-especially in cold weather climates. If the OP is in the Bahamas, now, and headed further south(warmer), what is the benefit of a multigrade oil? And, perhaps there will be a chance that switching to a straight 30W with a new oil filter may lessen oil consumption which was his original complaint. It's worth a try when faced with spending untold dollars with a mechanic. It is, to me, a win-win in either case. If it works . . . great! If it doesn't . . . nothing lost and you have a fresh oil/filter change. Good luck and safe sailing. P.S. There's always time for the mechanic.

[Cadence]

Originally Posted by four winds

It's my understanding that Yanmar changed the recommended oil to multi grade for all 3gm30f engines. The newer manuals reflect this, starting sometime around mid to late 1990's.

I'm not sure the grade of a good oil 30W or 5W40 is as important changing it as prescribed or sooner and doing the filter at the same time. The oil probably does not break down it just gets full of, no some contamination.

What can a oil change cost, peanuts compared to the investment in your engine.

[Cheechako]

Originally Posted by rognvald

For the sake of an academic argument, what is the purpose of a multigrade oil when used in a climate where the ambient temperature is rarely below 60 degrees? Multigrade oils were developed by the oil industry for engines that were used in a wide range of temperature conditions-especially in cold weather climates. If the OP is in the Bahamas, now, and headed further south(warmer), what is the benefit of a multigrade oil? And, perhaps there will be a chance that switching to a straight 30W with a new oil filter may lessen oil consumption which was his original complaint. It's worth a try when faced with spending untold dollars with a mechanic. It is, to me, a win-win in either case. If it works . . . great! If it doesn't . . . nothing lost and you have a fresh oil/filter change. Good luck and safe sailing. P.S. There's always time for the mechanic.

It doesn't need to be cold out for your engine to need a quick dose of oil pressure. Multi grad provides this, Most engine wear occurs on cold start up..... meaning starting up with the engine cold, not necessarily with it freezing out. Lower viscosity gets pumped quickly into the bearing journals etc.
For the OP: it is possible you have a cracked piston those engines are famous for. They often still run well, but the crack may go thru the lands where the oil ring resides.... causing oil consumption.

[four winds]

Actually, I'm certain a multi-grade oil is no substitute for regular oil changes.

Cheechako's comments are apropos in my opinion to the other issues mentioned.

[sailorchic34]

I'm oddly in Rognvald's camp on this one. Straight 30wt has more oil and less viscosity and friction modifiers. So it does provide very good protection and somewhat longer oil life in older diesel designs, compared to 15-40 or 10-30. Where temperatures do not drop below 45 degrees F, straight 30 wt works very well and does offer some benefits over multi-grade oils. Not lots, but there are measurable benefits (in warm climates).

Newer automotive engines have different designs on the oil delivery system and clearances on crank big and small ends are much tighter. So newer engine designs, of which the Yanmar GM series is NOT, require 5-30 and 0-30 oils. Partly because they got rid of the oil bypass relief valve in newer auto engines.

It's always better to have the least amount of viscosity modifiers in the oil as long as it meets the engine manufacturers design requirements.

I will note that when I had one piston with 3 bad rings (broken lands) back in 2013 I had lots of oil loss but no blue smoke. Blue smoke might be more indicative of worn exhaust valve guides as any oil entering from the ring bypass will be burned as part of combustion ( I was using a quart every 12-16 hours).

[four winds]

I'm not really on anyone's side. Just stated what Yanmar recommends.

A Yanamr GM isn't a modern design. But 5/30 and 0/30 isn't 15/40 either.