API CD spec engine oil

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DavidMcMullan

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My Yanmar 2GM20 manual specifies API CD 15W40 engine oil. However I understand that API CD became obsolete in 1996. Is it ok to use API CF 15W40 instead? Or does a marine diesel need something different?
David.

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Oil specs are "generally" retro compatible. There can be issues with high spec synths and semi synths with roller/ball big ends. The oil over lubs, and the bearings skid rather than rotate.

<hr width=100% size=1>Larry Botheras

Anderson 26 "Amber"
 
I don't see how you could cause any harm by using a better spec. oil eg. API CF. Although the newer oils tend to be aimed to achieve longer service intervals in road vehicles I shouldn't take advantage of that fact. In boats you really need to check the fuel filters and impellor and flush the cooling system once a year anyway so you might as well change the oil and filter as well. That way your engine will spend every Winter filled with clean oil.

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I have been told that it is definitely possible to have too good an oil, particularly using synthetic or semi synth. however, cd oil is still available, so why take any risk? better still, use yanmars own then there's no argument.

if you want cd types, try the classic car and bike suppliers.



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Why not spend the extra and buy the yanmar oil ?
Its always correct for the engine and isnt that much more money.

I dont work for them or sell anything to do with yanmar.

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My new Volvo 2030 manual states SAE 15/40 API CD, CE, CF, CF-4, CG-4.
(CD also listed for sail drive)
I use bog standard Castrol GTX at approx£7 / 5L Homebase.
My Volvo service agent say I should use Semi Syn.oil.
I am confused but can't see the Semi Syn. oil being much use in a low tech diesel engine?? and tend to agree with the other comment on lubrication problems.
Even the cheapest oils (typically B&Q own brands) seem to have a higher spec. and list all the API stuff similar to the branded lubricants.
Unless anyone suggests otherwise I am happy with the "CD spec".

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Yes I agree with you on my Volvo 2002 I use Castrol GTD 10W/40 cost about £11 in B&Q for 5L this meets or exceeds American Petroleum Instute CF. If you change your oil every year as I do it is not even necessary to use diesel oil as this only contains about 20% more anti acid additive or put another way it has a higher TBN (Total Base Number). If you only use about 20 gallon of diesel a year you are never going to use up the basic additive.
I would also point out that as far as I know Yanmar do not have a Lubricants Blending Plant, so they buy in from the oil majors and then have it put in there containers.
On the other hand do not buy the very cheap oils because........... erased for legal reasons.

Happy Christmas
Trevor


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Can I use this subject to ask a question.

Does anyone use semi. synthetic oil in their diesel engines and if so what are the advantages?

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Steve,
By buyig 'Yanmar' oil, are you not just buying their brand name mark up on an industry specification for lube oil ? Oil specifications are surely made for generic engine types.
David

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I have a Yanmar 2GM20 and use Castrol GTX diesel oil. Also have 2 Peugot 306 turbo diesels and use same oil in them. I understand semi-synthetic oil is only necessary in very modern very high performance diesel car engines but I am not an expert.

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apparently there is a some risk to using synthetic oil in an engine not designed for it - according to castrol tech dept advice to me.

from memory (which is not what it was) their comments were along the following lines. in a new engine it can prevent running in. real modern engines are finished to such high tolerances and with special bore surfaces so it doesnt matter. also, with older engines, it is poss for the additives in synthetics to form mild abrasive compounds which polish the bores

as indicated the advice came from castrol tech who make synthetics. they also commented that many jap engines were more "traditional" in their technology and therefore shouldnt be given synthetics. suggest you phone them.

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IMHO "saving" money on oil is usually a mugs game. I have used fully synthetic Mobil 1 on my 1966 Volvo MD1 for 10 years and it is great. The advantages for me are that its viscosity range 0w40 means that it is much easier to start from cold - and only with this oil can I hand crank it from cold. The engine does not need to warm up to get good oil flow going and this reduces wear (and glazing?) I suffered coolant starvation two years ago due to weed coming in the raw water inlet and (so far) seem to have had no adverse effects - would a lower spec non syntetic oil have failed at the unusually high temperature and allowed an engine seizure?? I believe the oil maker's claim that the oil virtually eliminates engine wear is sound and that the ever increasing performance of diesel engines is at least as much due to progress on lubricants as it is to engine design - so once your warrenty period is up and the engine is run in why buy the old stuff?
Martin of Seaesta of Whitby

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I worked for a car manufacturer for several years round the time Mobil 1 was introduced. We specified it in the engines and suddenly got a lot of warranty problems with excessive oil consumption. On stripping, they all had glazed bores. Mobil were consulted and the end result was that we specified a normal mineral oil for the first 6,000 miles and then Mobil 1 thereafter. I wasn't personally involved with the discussions so I don't know exactly what went on but the end result appeared to suggest that (at least with our particular engines) fully synthetic oil while running in wasn't a good idea.

As far as boats are concerned, mine has a roller bearing crank, big ends and mains and straight SAE 30 oil was specified. I can't get it now and just tend to throw any old 10-40 multigrade in. The engine is about 15 years old and will (I guess) have to be replaced when the cylider head rusts through (direct cooling). At this point, I imagine the bearings will all still be fine. I think what I'm saying is that I'm not too hung up on using the very best oil and chnging it every 10 minutes because I don't want part of my engine to last 200 years when I know the rest will be scrap in 20!

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Interesting points but I still think you are more likely to survive a blockage in your direct cooling water with better spec oil in the crankcase and the easier starting is important to me.
Engines often have higher oil consumption when brand new - possibly because the bores have machining marks deliberately left in them on manufacture. As these honing marks wear away oil consumption generally falls. Where the honing marks still in place on these glazed bores?

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I used to buy expensive semi-synthetic oils, but now go for 2.5l cans of 10/40 CF diesel oil sold in Carréfour. It costs about €7.80 and as I change the oil every 100 - 150 hours, the stabilisers are never exhausted. the Carréfour oil is produced by Total and sold under the Total label at x3 the price.

Incidentally it costs almost x2 to service the engine using Yanmar parts/oil when there are equally good, and frequently higher quality, substitutes out there.

Belt: Goodyear HD (my alternator puts out 100 amps and the Yanmar belt is useless)
Oil filter: any that fit the Mazda 323 (these come in a variety of sizes but a single base-thread). the smallest is the same as the 2GM20 one.

It's advisable, especially with the raw-water cooled 2GM20, to have the head off about 1000 - 1200 hours, replace the head gasket and clean out the waterways.
The engine has had so much power squeezed out of it thet the lands have been reduced to the point where blow-past takes place all too easily.
Apart from that they'll go on almost indefinitely at 1600 - 2000 rpm.

The only problem, as with all vertical twins, is that they're impossible to balance dynamically.


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Hi there,

As I understand it, the honing marks are put in deliberately by the manufacturer specifically to try and make it use LESS oil. There would be no sense in deliberately putting them there to make the engine use more oil! I think the idea is that the rough surface on the cylinder promotes rapid initial wear on any high spots between the rings and the bore so that they both mate better after a few thousand miles and that's why the oil consumption goes down. From what I remember (and I'm going back 10 years or so!) the concensus was that the Mobil 1 was just too good at keeping the moving parts out of direct contact with each other so this initial "bedding in" process was not able to take place. The resulting "blow-past" of combustion gasses "caramelised" the oil into a hard lacquery sort of stuff (technical eh?) which effectively turned into a sort of clear varnish. The cross hatching was therefore still present but under a layer of "glaze". The bores just needed a quick hone with an abrasive wheel and were fine after that.

I'm not an engine expert so this is all received wisdom but the facts is, several dozen engines burned significantly more oil after being run-in using Mobil 1 and the problem went away when they were run-in with a lower spec. of oil. I think that once the bedding-in has taken place, there are big advantages to using Mobil 1 thereafter and it is certainly harder to "cook" it than a mineral oil. That said, these were high peformance petrol engines rather than the sort of thing I've got which runs absolutely stone cold! I also take your point about hand starting when cold.

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