Best oil for Yanmar 2qm20

Tranona said:
Afraid you are wrong. Nothing to do with viscosity. All that signifies is the thickness of the oil and is independent of the formulation.

CF is the API (American Petroleum Institute) grading which is universally used for grading oils. The higher the last letter up the alphabet in general the more additives to cope with higher duty. The recommended oil for Yanmar is CD, which at the time (30 years ago) that these engines were designed was the appropriate grade. CF is today's equivalent, although in some places you can still get CD.

The additives in higher spec oils are actually potentially harmful in old style diesels, mostly being there to cope with high outputs, tight tolerances and long service intervals - none of which are relevant to our types of engines.

Smoky knackered engines are little to do with the oil used, more to do with the way they are used and abused. Typical yacht running of short bursts followed by long periods of neglect is not good for engines and no amount of fancy oil is going to make any difference. The engine in my old Bavaria did well over 3500 hours, moat of it in 7 years of chartering using CF 15/40 and never burned any oil and runs as well now as it did when it was new.

Suggest you have a look on Vyv Cox's website for a fuller explanation, or do a search as this subject has come up here many times in the past.

www.coxengineering.sharepoint.com Explanation of oils under engines.
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There are a lot of people who work in the oil industry who would disagree with you.
There has been a great deal of more informed debate in the world of motorbikes.
Where people do a lot of hours, and frequently dismantle things and see how they are wearing.
On a whole range of machinery, some of it a lot older than our Yanmars, which were in fact designed quite a while after Mobil 1 went on the market.
You talk about additives in high spec oils, but you haven't a clue what's been added to a recycled oil to get it in spec.
The Halfords oil states it needs changing frequently. There's a good reason for that.....

If you want to follow the traditional oil route (and there are plenty of bike people who do that with great success), I'd suggest a decent, well formulated brand like Miller's.

Vyv's website refers to one incident which is open to several interpretations.

I'm not expecting people on here to agree with me, but for anyone who is interested there is plenty of more informed discussion elsewhere.
 
lw395 said:
There are a lot of people who work in the oil industry who would disagree with you....
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In addition to daftly owning an old plastic boat, I daftly own an RX8 that I dote on as much as my boat. The oil discussions on the uk owners club forum are just as fraught as here (more so in fact), and lw396 makes a good point, lets hear from the oil companies. I've emailed Tim at Opie Oils, who has lots of good contacts and did loads of research on the RX8 for the UK owners club, lets see how he gets on.
 
Okay, Tim has kindly responded to my heckling:

While your engines might not require a good oil, they are likely to benefit from using something better than the cheapest thing you can find.

15w-40 mineral oils tend to be the cheapest things around, but they can vary in quality by a fair amount. The oil basestock can be more or less refined, some are recycled oil and the additive pack can be reduced. Also, less quality control in the production of some oils can mean that the oil doesn't meet the specifications listed on the can and may be a different grade to what is listed.

I have spoken to a few people with canal boats who insist on using an API CC or CD oil as apparently any newer specs than that can lead to the engine smoking, but it seems that the people I've spoken to have never had it happen to them and it's something they have heard of. In reality, you have to be careful with what is being written, there are lots of people putting things on forums without giving clear information (the oil might be thinner than the previous stuff or some other reason, but as it was a newer API spec, they blamed that). That is the only thing I can think of where a newer API C spec is seen as harmful, but I'm not convinced it's a problem.

A decent oil will have a better additive pack to help the oil last longer and protect better. It should also meet the specs and be the viscosity listed on the can. I'm not saying you need to go and buy top end race quality oil, but buying the cheapest thing you can find is not the best option for the engine.

Instead of a 15w-40 mineral oil, a 10w-40 semi is a good option. It will flow better when cold, so better cold start protection, and a semi will offer better all round protection than a mineral oil. It doesn't have to cost a fortune, but getting one from a reputable brand is worthwhile.
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I then pointed him to the COX engineering site and referenced the Yanmar/Shell technical reference, he responded with:

There are a couple of issues with older engines and new oils, but they are also irrelevant to an extent. The seals used in some older (pre-1970s) engines are not always compatible with some synthetic oils. I'm assuming the engines you are referring to are newer than those, but if not, the incompatible seals are not that common anyway.

The other thing is the level of antiwear additives. A lot of modern oils have reduced ZDDP levels (ZDDP is an antiwear additive) as the ZDDP can harm catalytic converters. API SM and SN oils have reduced ZDDP levels, but there are plenty of API SL oils in a 10w-40 grade. Also, in the oils with reduced ZDDP, there will be higher levels of other antiwear additives to make up for the reduced ZDDP.

With the information from Yanmar and Shell, I think they are playing it overly safe (as oil companies and engine manufacturers often do). There is the potential for issues with using some of the modern low emissions oils, but they tend to be thinner grades than 10w-40/15w-40, so it wouldn't be a sensible option to use one anyway.

One thing that some of the forum members need to consider is that an engine is designed to run on an oil viscosity, not synthetic or mineral oil. API specifications are important in many cases, but newer ones generally supersede the older ones anyway. Also, most 'synthetic' oils on the market are actually made from mineral oil. The mineral oil goes through a process called hydrocracking, which modifies and refines the oil so that it is far enough away from the original mineral oil that it is legally sold as synthetic. The synthetic component of a semi-synthetic is hydrocracked oil rather than a genuine PAO synthetic (so there would be none of the seal compatibility issues mentioned earlier).
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Interesting! I have also emailed French Marine to get their take on the above and see if they agree with the great and learned Tim.

I hasten to add I have no affiliation to Opie or French Marine other than I use Opie for the oil for my lovely, petrol guzzling, likely to catch fire at any given minute RX8.
 
MagicalArmchair said:
Okay, Tim has kindly responded to my heckling:



I then pointed him to the COX engineering site and referenced the Yanmar/Shell technical reference, he responded with:



Interesting! I have also emailed French Marine to get their take on the above and see if they agree with the great and learned Tim.

I hasten to add I have no affiliation to Opie or French Marine other than I use Opie for the oil for my lovely, petrol guzzling, likely to catch fire at any given minute RX8.
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I posted on here years ago that I have ignored the mineral oil recommended for my 3YM30s but used Semi-synthetic 15W-40 because it's better oil than any mineral oil but is the viscosity I need. I would use fully synthetic but I can find it at the correct viscosity.

According to your expert it looks as if my instincts from 45 years of maintenance were bang on the money :-)

Richard
 
RichardS said:
I posted on here years ago that I have ignored the mineral oil recommended for my 3YM30s but used Semi-synthetic 15W-40 because it's better oil than any mineral oil but is the viscosity I need. I would use fully synthetic but I can find it at the correct viscosity.

According to your expert it looks as if my instincts from 45 years of maintenance were bang on the money :-)

Richard
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You can buy fully synthetic with say a 10w40 or even a 5w40 rating.
That will be as thick as 15w40 when it's hot, but thinner when it's cold. That means its viscosity is more constant. Which is good. It will get around the engine more quickly on startup.
I would be concerned about taking things too far as you may get into oils optimised for long change intervals, with too many additives.
Personally I go for a semi synth as a reasonable compromise.
Need to get some oil for my bike soon.

There are full synth bike oils which are allegedy not too full of long life additives, as bike oil gets changed more often.
There are also race oils further down that road.
Bike oils are diiferent because bkes often have a sump full of gearbox and a wet clutch to cope with.

you need a Harley owner and a BMW k-series freak to have a proper rwo about this...
 
RichardS said:
I posted on here years ago that I have ignored the mineral oil recommended for my 3YM30s but used Semi-synthetic 15W-40 because it's better oil than any mineral oil but is the viscosity I need. I would use fully synthetic but I can find it at the correct viscosity.

According to your expert it looks as if my instincts from 45 years of maintenance were bang on the money :-)

Richard
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+1
 
hi ,i would never use bp vanelous oil in an old engine its ok if using from new , but not for old engines i destroyed a good dodge q with it ,it is high detergent and will clean the old engine that well it will have no compression soon after using hope this helps
 
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