Shell Rotella T6 5W-40 Full Synthetic Diesel for Yanmar 3GM30F

[a64pilot]

30 hours won't do it.
I find it hard to believe the one RPM thing too, my reason is because aircraft engines cruise at one set RPM and do so their whole life, but will pull more RPM at takeoff.
For instance the IO-540-W1A5D that was in my Maule would turn 2400 RPM at takeoff and I would cruise at 2200.
30 hours should have been an immeasurable amount of wear. Think of how many thousands of hours it takes to get enough of a ridge to catch your fingernail.
If you follow the manufacturers recommendation and run at high RPM every so often, you will clean out any carbon, possibly prevent bore glazing etc.

[RPZ]

Originally Posted by Cadence

It has nothing to do with the oil. Prolong running at one RPM can cause wear to one height on the cylinder wall and cause ring damage when RPM is increased. It is difficult the believe the minute difference in stoke is there but apparently is. It can only be a RCH an that is a scientific measurement.

It can only be attributed to poor oil, or insufficient oil level in the crank case. Cylinder walls are lubricated by splash. That is, the crank throws it around the case and it gets on the cylinder's liners as the piston goes up.

If this were due to prolonged running at steady rpm, cars and truck motors would be having catastrophic failures after moderate to high mileages on highways where engine rpm is often within a limited and low to moderate range.

Airplanes powered by piston engines are often run at a steady moderate rpm for extended periods. If this caused failures sudden high engine revs applied at takeoff, or a sudden climb needed to avoid a collision etc, they'd be falling out of the sky every day.

[Cadence]

Originally Posted by RPZ

It can only be attributed to poor oil, or insufficient oil level in the crank case. Cylinder walls are lubricated by splash. That is, the crank throws it around the case and it gets on the cylinder's liners as the piston goes up.

If this were due to prolonged running at steady rpm, cars and truck motors would be having catastrophic failures after moderate to high mileages on highways where engine rpm is often within a limited and low to moderate range.

Airplanes powered by piston engines are often run at a steady moderate rpm for extended periods. If this caused failures sudden high engine revs applied at takeoff, or a sudden climb needed to avoid a collision etc, they'd be falling out of the sky every day.

What was the question, oil? Is it possible aircraft change the load on the engine as do cars or trucks more than a boat? Or maybe the higher compression on a diesel? Just a question. I have seldom driven over 8hrs. without stopping for coffee or running into a traffic problem. If not an interstate a speed trap. PS, I-95 in your neck of the woods has been under construction for ever 64pilot.

[RPZ]

Originally Posted by Cadence

What was the question, oil? Is it possible aircraft change the load on the engine as do cars or trucks more than a boat? Or maybe the higher compression on a diesel? Just a question. I have seldom driven over 8hrs. without stopping for coffee or running into a traffic problem. If not an interstate a speed trap.

The premise was that an engine run at steady rpm would or could lead to a failure as the cylinders wear a shoulder at the top of their stroke. With high rpm, the micro changes in the outer orbit of the crankshaft and stretching of the connecting rods lead to a minute increase in the length of the stroke of the piston. Thus the rings hit the shoulder and are subject to an impact force.

We are creatures of habit, and on the highways, traffic permitting, tend to hold a steady speed of x mph. That equals a steady rpm. If the premise were true solely on the basis of steady rpm, vehicles with high highway cruising miles would suffer such failure more often than those of city and urban drivers where constant stopping and starting, and more variation in engine rpm is the norm. And that is just not the case.

Aircraft are another example.

And it still makes more sense to use the best modern oils because with the best filters and regular oil changes, they reduce cylinder wear by a great margin.

[Cadence]

Originally Posted by RPZ

The premise was that an engine run at steady rpm would or could lead to a failure as the cylinders wear a shoulder at the top of their stroke. With high rpm, the micro changes in the outer orbit of the crankshaft and stretching of the connecting rods lead to a minute increase in the length of the stroke of the piston. Thus the rings hit the shoulder and are subject to an impact force.

We are creatures of habit, and on the highways, traffic permitting, tend to hold a steady speed of x mph. That equals a steady rpm. If the premise were true solely on the basis of steady rpm, vehicles with high highway cruising miles would suffer such failure more often than those of city and urban drivers where constant stopping and starting, and more variation in engine rpm is the norm. And that is just not the case.

Aircraft are another example.

And it still makes more sense to use the best modern oils because with the best filters and regular oil changes, they reduce cylinder wear by a great margin.

I guess. My wife's car is three years old and is getting it's second oil change at 5100 miles. Those mile and a half trips will kill it.

[CarlF]

I don't think experieces with gasoline auto or aircraft engines tell us much as the compression ratio of a diesel is much higher (among other differences).

And the author pointed out that newer highway diesels have been modified to tolerate less lubrication from thinner synthetic oil (such as hardened camshafts) but that recreational marine diesels still use traditional metalurgy.

And both the engine manuracturer (Yanmar) and the oil manufacturer (Shell laboratories) told him that a synthetic blend could damage a traditional marine diesel like the 2GM (even a new one)

I too found this surprising - but the explanation seems plausible. It would not be the first time that the special needs of the tiny marine market has been ignored or forgotten.

I think I'll stick with the Rotella dino oils that have served me so well for decades.

[xtphreak]

Originally Posted by evm1024

One more thought Rotella and Delo are intended for diesel engines specifically. Best to stay with an oil designed for Diesels.

Diesel Engine Lubricating Oil
^.......^........^.............^

New to this site, old to almost everything else

Rotella 15W-40 is a "universal oil"

Look at the seal on the jug for applicable usages.
It's even gotten the JASO-MA (Japanese Automotive Standards Organization -Motorcycle A) rating.
I've used it in motorcycles, gas trucks and boats for years.
My 1999 Triumph Tiger 885 calls for synthetic 15W-40.
Only available then from Mobile One (Triumph branded) @ $60/gal!
It's now got 115,000+ miles on the original, untouched (save valve adj and oil changes) engine.

want to learn about oil (a most contentious subject)?

www.bobistheoilguy.com

[Cadence]

Originally Posted by CarlF

I don't think experieces with gasoline auto or aircraft engines tell us much as the compression ratio of a diesel is much higher (among other differences).

And the author pointed out that newer highway diesels have been modified to tolerate less lubrication from thinner synthetic oil (such as hardened camshafts) but that recreational marine diesels still use traditional metalurgy.

And both the engine manuracturer (Yanmar) and the oil manufacturer (Shell laboratories) told him that a synthetic blend could damage a traditional marine diesel like the 2GM (even a new one)

I too found this surprising - but the explanation seems plausible. It would not be the first time that the special needs of the tiny marine market has been ignored or forgotten.

I think I'll stick with the Rotella dino oils that have served me so well for decades.

You and I. But then, I'm also a dino.

[RPZ]

All diesels are by design and function high compression. That has no bearing on how a modern synthetic oil would affect wear or cause damage. Perhaps Yanmar and Shell could explain how they think modern synthetic oils could literally damage a motor. As I have already pointed out, and I would like hear any rebuttal, engine wear in regards to oil is determined by certain factors. Film strength, flow, pressure ( to pressure fed components), viscosity at specified temp ranges etc. For an oil to literally damage an engine there has to something inherent to the oil that attacks metal, or impedes the mechanical operation physically. It does not add up without a specific explanation.

[Cadence]

Originally Posted by RPZ

All diesels are by design and function high compression. That has no bearing on how a modern synthetic oil would affect war or cause damage. Perhaps Yanmar and Shell could explain how they seem oils could literally damage a motor. As I have already pointed out, and I would like hear any rebuttal, engine wear in regards to oil is determined by certain factors. Film strength, flow, pressure ( to pressure fed components), viscosity at specified temp ranges etc. For an oil to literally Ramage an engine there has to something inherent to the oil that attacks metal, or impedes the mechanical operation physically. It does not add up without a specific explanation.

I hope someone can answer that if at all true?

[RPZ]

The only thing I can think of is that it might chemically attack very old seals.

[Cadence]

Originally Posted by RPZ

The only thing I can think of is that it might chemically attack very old seals.

An excellent thought.

[CarlF]

Please read the link -

Oil for yacht engines

In particular, it gives two "explanations" for why synthetic oils could damage old design marine diesels....

"In the drive for improved fuel economy it is now common for lubricant viscosities as low as 5W-30 and even 0W-30 to be specified for car engines (which have specially hardened engine components). The disadvantage of these low viscosities is that separation of lubricated components is reduced and wear increased." (Remember that the OP's question was about using a 5W synthetic oil)

And:

"They (the Yanmar and Shell engineers) went so far as to say that we should never use synthetics in old design engines since there were components in the oil that could cause accelerated wear" (presumably the "components" are in the complex additive packages used in synthetic oils)

I'm no oil expert, but this certainly sounds plausible.

[RPZ]

Originally Posted by CarlF

Please read the link -

Oil for yacht engines

In particular, it gives two "explanations" for why synthetic oils could damage old design marine diesels....

"In the drive for improved fuel economy it is now common for lubricant viscosities as low as 5W-30 and even 0W-30 to be specified for car engines (which have specially hardened engine components). The disadvantage of these low viscosities is that separation of lubricated components is reduced and wear increased." (Remember that the OP's question was about using a 5W synthetic oil)

And:

"They (the Yanmar and Shell engineers) went so far as to say that we should never use synthetics in old design engines since there were components in the oil that could cause accelerated wear" (presumably the "components" are in the complex additive packages used in synthetic oils)

I'm no oil expert, but this certainly sounds plausible.

The "30" number is the thickness of the oil. The first number is really only an indication for a certain temp range in which flow rate will be sufficiently maintained. Thus 5-30 would be better for cold starts at say 10 deg Fahrenheit than say 15-30. Otherwise *film strength* which separates components is the same. In a warm climate you can use straight 30.

And

If their crank bearings, connecting rod bearings, cylinder walls, pistons, piston rings, valves etc are made of some metals that are not the steels and alloys everyone else uses from John Deere to Isuzu, Yanmar should explain. A new Yanmar costs, what, $15k and up? What are you getting that kind if money?

But regardless, basic steels, unhardened, and alloys are not chemically attacked by any components of synthetic oil, and oil properly directed will prevent wear. How much wear is dependent on the protective film of oil under load; viscosity - thickness, film strength etc of the oil. This determines wear. If the oil is not maintaining a film separating contact metal components it is not because it is synthetic or mineral based. It has to be something else.

All this talk about "modern engines" is irrelevant, high performance synthetic oils have been around for decades. If there was some problem using them in vintage motors of any kind it would have surfaced a long time ago.

[gleason99]

i changed to T6 last November and after about 150 hours now my rear oil seal is leaking. Coincidence? The engine has about 4000 hours and I had been using normal non-synthetic Shell Rotella before this. Anybody have any thoughts on this?