andyj301
Active Member
Is fully synthetic lube oil good or bad in a Yanmar 3YM30? I have read of the perils of synthetic oil in a 2GM. The engine is in a yacht I am looking to buy, the oil on board has api cf4.
Fully synthetic lube oil in Yanmar 3YM30
- Thread starter andyj301
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RichardS
N/A
I doubt whether you will get a definitive answer to your question.
I'm a synthetic oil afficionado but I have refrained from using fully synthetic oil in my 3YM30s because of the low viscosity compared to the Yanmar recommendation. Most posters will use 15W-40 mineral oil and change it annually although I and a few others use 15W-40 semi-synthetic. If there were a 15W-40 synthetic available at a reasonable price I might be tempted but there isn't.
I think one Forumite is using fully synthetic in a YM engine but that's the exception rather than the rule.
Richard
I'm a synthetic oil afficionado but I have refrained from using fully synthetic oil in my 3YM30s because of the low viscosity compared to the Yanmar recommendation. Most posters will use 15W-40 mineral oil and change it annually although I and a few others use 15W-40 semi-synthetic. If there were a 15W-40 synthetic available at a reasonable price I might be tempted but there isn't.
I think one Forumite is using fully synthetic in a YM engine but that's the exception rather than the rule.
Richard
oldharry
Well-Known Member
Try Googling it. Theres an interesting article on over specced oils by our forum Guru Vyv Cox here: https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx
A quick glance down the first page of Google suggests that fully synthetics are not generally suitable for yacht engines, and even semi synthetics are questionable for older engines.
The feeling seems to be that modern synthetics are designed for engines that run at higher temperatures than most older design yacht engines, so do not give proper protection. This is to to do with the design working temperature and stresses of the moving component, not the efficiency or otherwise of the cooling system.
A quick glance down the first page of Google suggests that fully synthetics are not generally suitable for yacht engines, and even semi synthetics are questionable for older engines.
The feeling seems to be that modern synthetics are designed for engines that run at higher temperatures than most older design yacht engines, so do not give proper protection. This is to to do with the design working temperature and stresses of the moving component, not the efficiency or otherwise of the cooling system.
lpdsn
Well-Known Member
There's regular poster on this forum, Vyv Cox, who has posted advice on his website. No doubt he'll be along soon.
https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx
I don't think there's anyone on the forum that would argue with Vyv, I certainly don't have the background to do so, so if you want a contradictory position you'd have to look at other forums then guess which one is right.
Anyway, the gist of it as I understand it, is that high TBN synthetic & semi synthetic oils increase wear in generally cold-running yacht engines. It probably isn't a big deal if short term. You can get engine tests as part of the survey (they use a sample of the oil, so don't let the current owner replace it). Probably just a case of buying the boat and doing an oil change.
PS Old Harry beat me to it.
https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx
I don't think there's anyone on the forum that would argue with Vyv, I certainly don't have the background to do so, so if you want a contradictory position you'd have to look at other forums then guess which one is right.
Anyway, the gist of it as I understand it, is that high TBN synthetic & semi synthetic oils increase wear in generally cold-running yacht engines. It probably isn't a big deal if short term. You can get engine tests as part of the survey (they use a sample of the oil, so don't let the current owner replace it). Probably just a case of buying the boat and doing an oil change.
PS Old Harry beat me to it.
lpdsn
Well-Known Member
PS Mineral API CD is readily available on Amazon from a German source.
BoyBlue49
Well-Known Member
If it is a new engine then it will probably never run in. Slow revving engines work best with mineral oils, use the spec that the manufacturer recommends then you can't go wrong.
Synthetic oils were introduced mainly for high revving turbo performance engines. ie. Cars producing 100+ bhp per litre benefit from this type of oil.
Synthetic oils were introduced mainly for high revving turbo performance engines. ie. Cars producing 100+ bhp per litre benefit from this type of oil.
andyj301
Active Member
Thank you all for your replies.
Reading on the Cox Engineering website is what worried me, a semi synthetic basically ruining an engine in 30hrs! The confusion was due to the 3YM30 being a more modern engine and reading somewhere about Yanmar oil now being too advanced for older GMs.
The engine in question only has 158.4hrs (in 9 years!) on the clock and the oil is so clean I struggled to see it on the dipstick. This could mean it has recently been changed but I'll still get it tested, thanks lpdsn for the tip.
Reading on the Cox Engineering website is what worried me, a semi synthetic basically ruining an engine in 30hrs! The confusion was due to the 3YM30 being a more modern engine and reading somewhere about Yanmar oil now being too advanced for older GMs.
The engine in question only has 158.4hrs (in 9 years!) on the clock and the oil is so clean I struggled to see it on the dipstick. This could mean it has recently been changed but I'll still get it tested, thanks lpdsn for the tip.
vyv_cox
Well-Known Member
Without going into the technicalities here, covered on my website (thanks for the promotion from several posters), using synthetic oil in a yacht engine is throwing money down the drain. Synthetics are used in high performance engines because their oxidation resistance, viscosity retention and thermal stability are an order of magnitude greater than can be achieved with the best mineral oils. The standard oxidation test is the RBOT (rotating bomb oxidation test) in which a vessel containing the oil is rotated while being heated to quite a high temperature. A typical figure for a mineral oil is around 200 hours. I know of a test on a synthetic that was stopped at 5000 hours with no deterioration. There is little use for such properties in a yacht auxiliary.
lw395
Well-Known Member
The manual for the engine can be downloaded here:
http://www.yanmarmarine.com/Products/Sailboat-and-small-craft-engines/3YM30AE-426/
Somewhere around page 30 it says CF oil is good.
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Or if you cross the Channel, at "Roady" automotive stores in France for less than £10 / 5L. I bought some 2 weeks ago after balking at Yanmar own brand's £45 price tag.
sailorman
Well-Known Member
But, some semi synthetics are no more £s than mineral oils when on offer. So in that case not such a waste of money
sailorman
Well-Known Member
Yanmar Volvo etal do not actually manufacture / blend oils or make oil filters
lw395
Well-Known Member
You might find some really cheap recycled oil labelled 'CD' in a pound shop come to that.
A new engine is north of £4500, even expensive oil is pretty cheap.
andyj301
Active Member
Thanks for more helpful replies. Even with the very low hours it'd be daft not to ask.
From Vyv Cox's post it seems synthetic in a 3YM30 is more overkill than destroyer of the engine. Please correct me if I got this wrong.
Sounds like an oil change could be first on my list of jobs.
From Vyv Cox's post it seems synthetic in a 3YM30 is more overkill than destroyer of the engine. Please correct me if I got this wrong.
Sounds like an oil change could be first on my list of jobs.
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I don't think you can find CD anywhere in the UK, actually. For me there is a line between paying for quality and having the pis$ taken, and Yanmar cross this line and then some. I have zero knowledge of the details of engine oils but I did take the time to research the subject through Vyv's site, amongst others.
Fear through ignorance is a wonderful way to extract £££ from the gullible.
BTW, if you can supply me with a new 3YM30 for anything like £4.5k I'll bite your hand off
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dom
Well-Known Member
lw395
Well-Known Member
No chance, that's all sold to Wetherspoons.
Some of it very possibly comes from Wetherspoons kitchens.
lw395
Well-Known Member
I don't think you can find CD anywhere in the UK, actually. For me there is a line between paying for quality and having the pis$ taken, and Yanmar cross this line and then some. I have zero knowledge of the details of engine oils but I did take the time to research the subject through Vyv's site, amongst others.
Fear through ignorance is a wonderful way to extract £££ from the gullible.
BTW, if you can supply me with a new 3YM30 for anything like £4.5k I'll bite your hand off
You can find lots of oil in the UK that meets the CD spec.
Most oil which passes higher 'C' specs will automatically pass the tests required to be labelled as 'CD'.
That is why it's an obsolete spec.
However if you want something that actually says CD on it, then Opie oils will sell you some.
http://www.opieoils.co.uk/p-6504-motul-inboard-tech-4t-15w-50.aspx
As will many other places.
Good CD oil is not much cheaper than any other good oil.
You still need a well developed detergent and other additive mixture and good quality control.
So good oil from a respected brand is important to me.
That's if you value your engine and want to keep it a long time.
If you're happy saving a tenner by buying unbranded rubbish, that's up to you.
A lot of people are drawing too obvious conclusions from Vyv's site.
We could ask ourselves why the two cyclinders (or was it 3?) in the engine that people bang on about had different outcomes?
They had the same oil.
Think about it.
I think someone was had over.
By the way, if you think my views and Vyv's are contrary, you might fight it amusing to google 'synthetic harley oil' or similar, you can find some quite funny opinions on oil!
pvb
Well-Known Member
I used to use synthetic or part-synthetic oil in the turbocharged Volvo 2003T in my old boat, primarily to give added protection to the turbocharger. When I sold it, the engine had done over 2000 hours, was 24 years old, and was still running fine with its original turbo.
Halo
Well-Known Member
Most big supermarkets carry a suitable and relatively inexpensive mineral oil. Typically it's CF spec which is better for your engine than CD. I have used the Tesco 15w40 in my 3YM30 for years and it's fine. If you want your engine to last don't let it idle and change the oil frequently.