Yanmar 2GM20 Oil

[RichardS]

Owning a Yanmar I decided to ask BP's advice on this and the use of road diesel which includes a percentage of FAME. Wrt FAME, BP's answer was as clear as day and I have previously summarised and posted the reasoning.

In terms of engine oil, their advice was that modern engines are very different to older ones, operate at finer tolerances, higher temperatures, etc. The message was that the use of synthetic "may or may not" do harm, and that this would be difficult to determine ex ante in the absence of a detailed discussion between the oil co. and the engine OEM. Moreover, their advice was that if the engine specified regular changes of 'low spec' oil, then one should do that and not be influenced by the 20,000 oil change interval on modern cars.

It would therefore seem that the question is less one of cost-benefit analysis and more one of:

"Do you feel lucky punk ....well do ya?" ​

Errrr ....no. It's more a question of have you ever stripped down an engine which has been run solely on mineral oil and one which has been run solely on synthetic oil ..... well, have ya?

BP are perched comfortably right bang on the sharp point of that fence ..... exactly as you would expect. As far as the oil rather than diesel discussion goes, that's certainly not my definition of "as clear as day".

Richard

 

[dom]

Errrr ....no. It's more a question of have you ever stripped down an engine which has been run solely on mineral oil and one which has been run solely on synthetic oil ..... well, have ya?

BP are perched comfortably right bang on the sharp point of that fence ..... exactly as you would expect. As far as the oil rather than diesel discussion goes, that's certainly not my definition of "as clear as day".

Richard

Nope, never stripped down anything more complicated than an 8hp 2T outboard. Re BP, I thought there advice re FAME diesel was indeed as clear as day on how to keep diesel healthy in a marine environment.

Not sure what you mean about being perched on the fence, but their point on the use of non-specified oils was basically that it is difficult to be sure ex ante; you might get away with it, you might not, but get it wrong and the damage can be catastrophic ...hence my Dirty Harry comparison

I guess for a non-engineer like me; if an oil major, Yanmar, and our very own Vyv Cox all line up on the same side of the proverbial fence

...well why leap over it

 

[Tranona]

Boat auxiliaries rarely wear the things that are lubricated by the oil - they die of lack of use and neglect (or both). There is no logical CBA for different types and cost of oil - that is the extra life value exceeds the lifetime cost of the more expensive oil. There is just not any reliable data on which to base such an analysis.

The only CBA offered is the simplistic one from RichardS who buys more expensive oil and changes it less frequently. i say simplistic because how do you "prove" that the engine is better off with this regime? The only benefit I can see is a saving of maybe 1 hour every other year in changing the oil and filter and the cost over time is the same (assuming the oil is twice as expensive).

The key thing for me is that the engines are lifed for 8000+ hours using the (cheap) recommended oils. This is 50 years of typical use in this application. So, what is the benefit (other than saving maybe an hour every other year) of using a non recommended oil? Is there evidence that life will be extended by 10 or 20 years?

 

[RichardS]

Nope, never stripped down anything more complicated than an 8hp 2T outboard. Re BP, I thought there advice re FAME diesel was indeed as clear as day on how to keep diesel healthy in a marine environment.

Not sure what you mean about being perched on the fence, but their point on the use of non-specified oils was basically that it is difficult to be sure ex ante; you might get away with it, you might not, but get it wrong and the damage can be catastrophic ...hence my Dirty Harry comparison

I guess for a non-engineer like me; if an oil major, Yanmar, and our very own Vyv Cox all line up on the same side of the proverbial fence

...well why leap over it

I did refer to the advice on oil being on the fence .... "may or may not do harm", "difficult to be sure", "may get away with it" ..... rather than the diesel recommendation.

The problem with "sitting on the fence" is that BP are not giving you the full picture .... in fact, they're giving you no picture at all. What they could equally say is "May or may not do good".

Which is where I come in because my experience tells me that in engineering terms it does do good but in cost terms it might not. However, these are different individual parameters to be applied to each of those benefits/dis-benefits which is where the CBA comes in.

Personally, I would use the more expensive oil in my Yanmars even if I changed it every year because I believe that the engineering benefits are worth paying for. The fact, that I don't change it every year simply edges over the benefit side a bit more. However, your CBA balance might be different.

I'm currently on my 3rd year with this oil. I have not added a drop since I changed it, the level is still identical on the dipstick and the oil is so clean that it is barely visible. I will not be changing it until it needs to be changed.

Tranona's point is generally right as it's difficult to "prove" without very expensive technical bearing and bore analysis just how much better for the engine the better oil might be, even if it is changed every year. However, having used synthetic oil, and only synthetic oil, since the late 1970's, I reckon that I've got a fair amount of experience to draw on.

Richard

 

[JumbleDuck]

As you know, I've never found any harm being created in older engines by using semi or fully synthetic but have always been amazed by how clean and carbon-free the engine remains internally ...

You should see what the insides of an LPG fuelled engine looks like. The oil comes out with exactly the same appearance as it went in.

 

[dom]

The problem with "sitting on the fence" is that BP are not giving you the full picture .... in fact, they're giving you no picture at all. What they could equally say is "May or may not do good".

Which is where I come in because my experience tells me that in engineering terms it does do good but in cost terms it might not. However, these are different individual parameters to be applied to each of those benefits/dis-benefits which is where the CBA comes in.

Personally, I would use the more expensive oil in my Yanmars even if I changed it every year because I believe that the engineering benefits are worth paying for. The fact, that I don't change it every year simply edges over the benefit side a bit more. However, your CBA balance might be different.

Richard

I think the CBA (cost benefit analysis) is a bit of a red herring as half an hour for an oil change and a few quid for oil are immaterial to a normal boating budget. The big ticket risk here is engine damage.

And here BP and Yanmar are indeed sitting on the fence to some extent; they advise that modern synthetic oil will probably not, but 'may result in catastrophic engine damage', as for example described over on Vyv's website.

I guess it's down to personal circumstances, but for someone like me, when one of the largest oil companies in the world lines up hard advice with the leading engine OEM whose engine I have installed in my boat

...well I basically just heed it!

 

[Tranona]

However, all you have is experience of the type that is the same over and over again. What you have not done is shown any material benefits of your strategy. Have you run any comparative tests of the same engines run under the same conditions for the same amount of time and measured any differences? I could say similar things about mineral oil. I ran one Yanmar for 20 years on the correct mineral oil with no discernable wear and one Volvo for 3500 hours with no problems. What does that tell me?

All you have shown in a broad brush way is that synthetic oil does not seem to do any harm but also seems to have no measurable benefits (but significant costs). So, why do you do it, unless the engine requires it because of its design?

BTW I use synthetic oil in my cars because that is what the manufacturer recommends.

 

[Steve_N]

Grade doesn't seem to be intrinsically linked to viscosity any more - I find it all very confusing.
For example a fully synthetic 5w30 A5/B5 oil is thinner (has a higher or lower, whichever it is!, HTHS Viscosity) than a fully synthetic 5w30 A3/B4 oil and may be too thin for engines not designed to use it. Both 5w30 though.

Then there's the confusion that exists over hydrocracked mineral oils (API Group III) being allowed to be labelled as 'fully synthetic'. It would be easier for everyone if that title was restricted to Group IV PAO oils, probably what most people think they are getting when they buy 'fully synthetic' rather than heavily processed mineral oil.

It easy with cars because you can just buy oil using the manufacturer's specification e.g. VW 507.00, but for all other engines it's become a minefield.

 

[B58]

Hi, I’ve been looking at past threads on this and most are old and not very conclusive, what oil are people using for the 2GM20, both engine and gear box, manual appears to suggest the same in both but they s seems to be a little strange.

Would like simple answer if possible not deep technical one

Your right, you can use the same oil for both the engine and the gearbox use either Yanmar 15w40 or Shell Rimula 15w40 is ideal. Yanmar do also quote a mono grade oil for your KM2P gearbox which is SAE30 both Yanmar or Shell can supply. They are both mineral oils.

 

[MagicalArmchair]

Short answer: Shell Rimula R4 - https://www.olieonline.co.uk/shell-rimula-rt4-x-15w-40-20-liter

Long answer: I had a dust up with a marine engineer who challenged the use of the above oil in our little, old, 2GM20s. My late father was a shipwright and always used it (well, R3), but that was the only basis I had for recommending it, so I wrote to the good people at Shell and was astonished at the level of detail (and sheer oil geekery) they responded with.

Hi Mark,
Thank you for contacting Shell Technical.

I’ve coordinated with our Global Technical Support Team, please see below for their response.

Rimula RT4 X 15W-40 is a mineral oil with a BN of 10.5 & a sulphated ash content of 1.45%, so it is fairly highly alkaline.

Meanwhile, Rimula R3 X 15W-40 (CI-4) typically had a BN of 11, & a sulphated ash content of 1.5.

So, in terms of reserve alkalinity the 2 brands were very similar, although some earlier versions of Rimula R3 X (CH-4) were marginally lower. Really little in it.

Sulphated ash defines a test procedure that indicates the amount of metallic additives in an oil. In practice these additives burn to form ash that can deposit on pistons & valves, and to form particulates that are emitted from the exhaust.

Simply put, bore polish is a wear phenomenon (unlike bore glazing, which is lacquer-induced) & is a result of hard carbon build-up in on the piston crown land. The search for a remedy for this resulted in the Americans & the Europeans approaching the issue in different ways.

The Americans decided to increase the crevice volume (the clearance between piston crown land & the cylinder) so that carbon build up would take longer to fill the space (causing polishing). Some designs use a tapered crown to reduce this even further. The type of oils recommended for this design are low ash oils.

The Europeans decided that a better approach was to prevent carbon build up on the crown land in the first instance. To do this they specified highly detergent oils that would keep the piston clean, & free of deposits. These type of oils are high ash oils.

Japanese designs (like Yanmar) echoed their European counterparts.

Generally, American Heavy Duty engines require low ash oils. European/Japanese Heavy Duty engines require high ash oils.

The Yanmar 2GM20 is a small, 2 cylinder, normally aspirated, light duty diesel engine. The original OEM requirement was for API CC performance oils, mainly monogrades, but 20W-40 multigrade also being acceptable. Over the years demands by OEMs to meet stricter & stricter performance criteria have resulted in these low performance oils disappearing from the market place. While higher tier oils are usually backward compatible with these low tier oils, they are often an over-kill. Where one can encounter problems is when a highly detergent oil is used for the first time in an old engine that has run for years on a low-tier oil, when suddenly the detergents get to work cleaning up the ring-belt area, leading to excessive oil consumption.

It is not wrong to say that Rimula RT4 X is suitable for use in these little engines, but there may be lower tier oils available that will do the job perfectly well.

Having said that, there’s no reason why Helix HX5 15W-40 (API SN/CF) should not work satisfactorily (even if it is not a 20W-40) in these engines. Whether it will actually work better than Rimula RT4 X is debatable.

I hope this helps. Should you have any more questions or concerns, please feel free to revert back to us.

Regards,

Ina
Technical Help Desk - UK

 

[vyv_cox]

Thanks Mark. My good friend Sue is also in this department and I refer technical oil questions to her sometimes. Only problem is that the formulations of Shell (and probably others) products change over the years. In some cases, notably hydraulic oils, later ones are incompatible with older ones. Almost certainly not the case with engine oils but the base numbers certainly change.

 

[JumbleDuck]

"Where one can encounter problems is when a highly detergent oil is used for the first time in an old engine that has run for years on a low-tier oil, when suddenly the detergents get to work cleaning up the ring-belt area, leading to excessive oil consumption."

Ah-ha. That sounds like an awful good explanation for what I experienced. Thanks for (re)posting this.

 

[vyv_cox]

Ah-ha. That sounds like an awful good explanation for what I experienced. Thanks for (re)posting this.

There are many such warnings on 'classic' car forums.

 

[PaulRainbow]

I find it hard to understand why anyone would use an oil that is a different spec to that which the manufacturer of the engine states should be used

Makes no sense and switching to detergent oil is a sure fire way to kill an engine. Excessive oil consumption is only one problem, it can also cause problems with just about any moving part in the engine.

 

[RichardS]

I find it hard to understand why anyone would use an oil that is a different spec to that which the manufacturer of the engine states should be used

In my engines I'm using use DOT5.1 brake fluid, GL5 gear oil, OAT antifreeze, synthetic oil, silicone hoses, nitrile seals, etc etc etc, none of which are recommended by the engine manufacturer ..... for obvious reasons.

As for "killing engines", quite the opposite. My engines have all been running on synthetic for 40 years, look like brand new internally, have zero oil consumption, have never had to replace an engine bearing, all run without any bearing wear noise and all do over 100k miles. If that's killing them, then I'm all in favour of death.

Richard

 

[RichardS]

There are many such warnings on 'classic' car forums.

And there are many classic car forums which warn one about taking any notice of such warnings.

Richard

 

[RichardS]

Short answer: Shell Rimula R4 - https://www.olieonline.co.uk/shell-rimula-rt4-x-15w-40-20-liter

Long answer: I had a dust up with a marine engineer who challenged the use of the above oil in our little, old, 2GM20s. My late father was a shipwright and always used it (well, R3), but that was the only basis I had for recommending it, so I wrote to the good people at Shell and was astonished at the level of detail (and sheer oil geekery) they responded with.

Good advice from Shell although I'm a bit more picky about viscosity grades than they are. However, it's not quite the same as we're discussing because synthetic oils give rise to much less carbon build up than mineral oils anyway. A high-detergent oil mineral oil will also result in cleaner internals and might clean up existing deposits, so although both result in a "cleaner" engine, the mechanism is not the same.

Richard

 

[RichardS]

However, all you have is experience of the type that is the same over and over again. What you have not done is shown any material benefits of your strategy. Have you run any comparative tests of the same engines run under the same conditions for the same amount of time and measured any differences? I could say similar things about mineral oil. I ran one Yanmar for 20 years on the correct mineral oil with no discernable wear and one Volvo for 3500 hours with no problems. What does that tell me?

All you have shown in a broad brush way is that synthetic oil does not seem to do any harm but also seems to have no measurable benefits (but significant costs). So, why do you do it, unless the engine requires it because of its design?

BTW I use synthetic oil in my cars because that is what the manufacturer recommends.

You seriously underestimate my experience.

I have stripped down engines which have run on mineral oil for their entire 100k existence and stripped down engines which have run on synthetic oil for their entire 100k existence. It's like chalk and cheese and, although it might, as a minimum, only be a visual difference, if I showed you those two stripped down engines and asked you to choose which one you wanted me to rebuild for you, I am 100% certain that you would choose the one run on synthetic oil.

Richard

 

[JumbleDuck]

There are many such warnings on 'classic' car forums.

I was quite surprised when my friendly DS guru recommended 10w40 semi-synthetic, but it doesn't seem to be doing any harm, and it's slightly cheaper than the 20w50 mineral I buy for the Herald.

I find it hard to understand why anyone would use an oil that is a different spec to that which the manufacturer of the engine states should be used

Lots of good reasons. The original oil may be difficult to get hold of. Better oils may have come along in the meantime. Sorry to return to the DS, but many people claim that it's sacrilege to use anything other than Michelin XAS (at ~£200 a pop), and growl at me for using modern Continentals ... which perform better, last longer and cost around 1/3 as much.

 

[richardabeattie]

This thread is getting out of hand. Let's get back to basics. Tranona said "Simple answer is a 15/40 mineral oil to CF spec". Sounds good enough to me. So where do |I go to buy it?