jfkal
Active member
Yanmar recommends CD classified oils. Now a supplier tells me that this is no good and his oil which is CF-4 is much better. Any comments?
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Diesel Engine Oils
- Thread starter jfkal
- Start date
Avocet
Well-known member
Hopefully someone better qualified than me will answer this because I wouldn't mind an answer too! Mine needs straight SAE 30 oil and almost everything these days is a multigrade (which I have been using this last few seasons and it seems happy enough!) Anyway, All I know is that the "D" classification was an earlier specification than "F" for diesel engine oils. I think "F" takes into account the demands of modern turbo diesel engines - very high temperature resistance round the turbo, and maybe a few other things like reduced bearing clearances due to the engine being made to better tolerances and not being as worn. My gut feeling is that your engine doesn't NEED the extra protection of the newer oil but I don't know whether the newer oil would do it any harm. I don't THINK it will! My quandry is that it tends to be the cheaper brands that you've never heard of (like "Lube-O-Max" or something corny which you get in your local motor factors for £5.99 / gallon!) that still advertise the older grading letters on the can and I'm always a bit suspicious of these!
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vyv_cox
Well-known member
API CD is now obsolete, although it seems to be taking manufacturers of both engines and lubricants to catch up with this information. The "official" substitute is CF-4 for normal fuels and CG-4 for low sulphur versions.
One of the main differences between API grades is their Total Base Number, TBN. High TBNs are designed to neutralise the organic acids produced in high output, turbocharged truck engines, whereas low TBNs, such as in API CD grades, are ideal for normally-aspirated, fairly lightly rated engines that rarely operate for long periods, such as yacht auxiliaries. So in this respect a CD is ideal for us. However, insisting on a CD grade may mean that other improvements in the packages of more modern products in the CF-4 grade are not present. Using higher rated oils in low-rated engines can lead to increased rates of bore wear. I still use CD in my Yanmar.
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One of the main differences between API grades is their Total Base Number, TBN. High TBNs are designed to neutralise the organic acids produced in high output, turbocharged truck engines, whereas low TBNs, such as in API CD grades, are ideal for normally-aspirated, fairly lightly rated engines that rarely operate for long periods, such as yacht auxiliaries. So in this respect a CD is ideal for us. However, insisting on a CD grade may mean that other improvements in the packages of more modern products in the CF-4 grade are not present. Using higher rated oils in low-rated engines can lead to increased rates of bore wear. I still use CD in my Yanmar.
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tr7v8
Active member
Vyv is obviously far more qualified than me to answer the techie bit, but a lot of agricultural engines still use a monograde oil so a trip round the average farmers supplies place should yield good results. Also Millers do a range of oil for classic machinery. Very High quality oils can case problems as the additives are designed for the high revving high temp type of engine.
Jim
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Jim
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jfkal
Active member
Believe it or not., The stuff is hard to come by in Singapore. Its either low grade cheapo stuff or CF-4. Which one would you use?
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vyv_cox
Well-known member
In that case I would definitely use CF-4. Good quality Singapore lubricants are some of the best available, whereas I guess that the bottom end of the market place could be very dubious. Yanmar's own CD grade is a good product.
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jfkal
Active member
Thanks a ton 4 the advice. Thought I better ask so I do not screw up my new engine on the first oil change
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Blue_Blazes
New member
Avocet, What engine is yours that uses sae30? My previous engine was a series 53 Detroit Diesel, which used either sae30 or sae40 grade. I can't remember why, but there were dire warnings in the workshop manual for that engine warning AGAINST the use of multigrade oils. If I were you I'd seek expert opinion as to whether it is safe to run your engine on multigrade. Bill W.
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Avocet
Well-known member
It's a BMW D12 single cylinder. It doesn't have an oil pump. Everything is splash lubricated (roller bearing crank & mains). This is reassuring when sailing heeled but I've always used a multigrade and it seems happy enough! I wouldn't mind an excuse to get another engine though!
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G
Guest
Guest
had this discussion about the oil in my old motor bike, which has roller mains. i was told by an ex oil industry man that they produce a 15/40 multigrade by taking a straight 15 grade oil and adding viscosity enhancers. trouble is that the roller bearings chop up the molecules in these viscosity enhancers and you end up with a straight 15 grade after a while. so if yourengine really needs the 40 viscosity at op temperatures you have problems.
have no way of knowing if this is correct, but the man sounded convincing at the time.
maybe vyv can comment
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have no way of knowing if this is correct, but the man sounded convincing at the time.
maybe vyv can comment
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Avocet
Well-known member
I'm not an expert but I'd have thought that whatever a roller bearing could do to the long molecules would pale into insignificance compared to what an ordinary gear-type oil pump would do!
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vyv_cox
Well-known member
Viscosity Improvers
It's not quite as simple as that. Some base oils have naturally better VI properties, so manufacturers would tend to select them for lubricants. Monograde oils are a fairly narrow distillation cut, whereas selecting a wider cut will again benefit VI. VI improvers will almost always be added but sparingly.
There has been work done on centrifugal filters and some removal of long-chain additives was found. I don't know of destruction of molecules by rolling bearings and if you consider greased-for life bearings, where the amount of lubricant is very small compared with an engine, I doubt if it is ever a problem.
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It's not quite as simple as that. Some base oils have naturally better VI properties, so manufacturers would tend to select them for lubricants. Monograde oils are a fairly narrow distillation cut, whereas selecting a wider cut will again benefit VI. VI improvers will almost always be added but sparingly.
There has been work done on centrifugal filters and some removal of long-chain additives was found. I don't know of destruction of molecules by rolling bearings and if you consider greased-for life bearings, where the amount of lubricant is very small compared with an engine, I doubt if it is ever a problem.
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colvic
New member
Where has SAE gone? I used SAE 30 in our old Thornycroft 90, getting it from Agricultural suppliers as already mentioned.
With a new Mitsubishi based engine, non turbo, upto max six hours operation at a time what should I be looking for in the modern designating system, as I thought a general purpose multigrade for diesel engines would be OK.
Phil
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With a new Mitsubishi based engine, non turbo, upto max six hours operation at a time what should I be looking for in the modern designating system, as I thought a general purpose multigrade for diesel engines would be OK.
Phil
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G
Guest
Guest
I'm no expert either, but I recently had discussions with Barrus, Shell and Castrol regarding the lubricant for my Yanmar 3GM gearbox. Seems there two gearbox versions, mechanical and hydraulic, the former taking the same oil as the engine crankcase, the latter a special oil. Also seems most cruising yachts auxilliaries are equipped with the mechanical type (as is mine), which makes life easy.
Then came the question of the best oil to use in both crankcase and gearbox. Yanmar recommend no additives. I had been using Shell Helix, which Shell has now replaced, so may not be the same. Following discussion with Castrol engineer I have switched to Castrol GTD, which is a basic diesel motor oil without additives. I was advised to avoid Castrol GTD Plus and higher grades with additives because these are designed for road transport engines which spend much more time revving at different speeds, including idling, and are designed to take advantage of oil with additives for cleanliness and reduced wear. A marine auxilliary engine tends to run for long periods at a single cruising speed with a steady load, are not built to use oil with additives (Yanmars are quite an old design), and will eventually glaze if an advanced oil is used. Sorry to introduce that word glazing again, but that's what I was told by the "experts". Incidentally, plain Castrol GTD is sometimes hard to get - I had to order it thru my local Motaman. It is considerably cheaper in France at Carrefour.
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Then came the question of the best oil to use in both crankcase and gearbox. Yanmar recommend no additives. I had been using Shell Helix, which Shell has now replaced, so may not be the same. Following discussion with Castrol engineer I have switched to Castrol GTD, which is a basic diesel motor oil without additives. I was advised to avoid Castrol GTD Plus and higher grades with additives because these are designed for road transport engines which spend much more time revving at different speeds, including idling, and are designed to take advantage of oil with additives for cleanliness and reduced wear. A marine auxilliary engine tends to run for long periods at a single cruising speed with a steady load, are not built to use oil with additives (Yanmars are quite an old design), and will eventually glaze if an advanced oil is used. Sorry to introduce that word glazing again, but that's what I was told by the "experts". Incidentally, plain Castrol GTD is sometimes hard to get - I had to order it thru my local Motaman. It is considerably cheaper in France at Carrefour.
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