Bukh DV20 Diesel, Sulphur, Engine Oil - all very confusing

winsbury

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The modern lubrication requirements of a 1986 diesel BUKH DV20 engine and gearbox are perplexing... searching these forums and reading the manuals, wiki and https://coxengineering.sharepoint.com/Pages/Oilforyachtengines.aspx etc., have not helped much so here's the thinking so far:

  • modern (red) diesel has virtually no sulphur content compared to fuel which was around in 1986.
  • modern high performance and (semi)synthetic oils are very bad for old engines particularly low temperature direct cooled non-turbo ones but classic oils were intended for use with high fuel sulphur content .
  • Adding Fuel Set helps disperse water to avoid the dreaded bug, but it is not clear if it adds any sulphur or equivalent compounds.
  • It is still possible to find the obsolete CC and CD grade oils as specified in the original manual, but the chemistry is at loggerheads with modern fuel.

Bottom line is which is the right oil to put into the engine and gearbox of my aged engine to give it maximum life ?
 

bluevelvet

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I had a BMW 2 clyinder early 80s engine in my last yacht and the previous owner just used cheap supermarket diesel engine oil and always added a half cup of the engine oil to diesel fuel. I followed suit and had no problems with the engine over a seven year period. The engine had over 4000 hours when i sold and the engine ran and sounded great.
 

RichardS

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The fuel issue and the oil issue are different ones so no need to correlate them.

There have been many threads about where to get CD oils and Morris oils gets mentioned. However, those who prefer mineral oils on here often seem to use the cheap supermarket mineral 15W-40 type oils as these are seen as close enough.

I don't believe that the Fuel Set type stuff has a sulphur additive in it but I there might be additives that you can buy. However, millions of old engines are running around on modern diesel fuel without additives so I don't think it's a big issue.

Richard
 

No Regrets

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Stick with basic cheap oils of the correct viscosity. They have few additives, good 'stiction' from cold and will do the job. It would be hard not to do the job on an engine which was of an era of such old basic lubricants in fairness!

Don't be scared of Semi Synthetic stuff, it's normal mineral oil with additives, most of which are worthwhile.

The opposite is true of ultra modern engines, some which are designed to run on an exotic cocktail of lubricant, and in the case of Cars, with emissions controls are essential.

You have few worries!
 

vyv_cox

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I ran my Bukh DV20 throuhout the time I owned it on API CD 15w-40 oil. That was then, now API CD is less easily obtained in UK, so I would run it on API CF4, same viscosity.

The fuel issue is totally separate. Sulphur levels are lower than they were, so that high TBN oils are even less necessary than they were. API CF-4 has an acceptably low TBN that is compatible with modern fuels.
 

chewi

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I ran my Bukh DV20 throuhout the time I owned it on API CD 15w-40 oil. That was then, now API CD is less easily obtained in UK, so I would run it on API CF4, same viscosity.

The fuel issue is totally separate. Sulphur levels are lower than they were, so that high TBN oils are even less necessary than they were. API CF-4 has an acceptably low TBN that is compatible with modern fuels.



you confuse me there vyv
doesnt "Sulphur levels are lower than they were, so that high TBN oils are even less necessary than they were" imply a connection between oil a fuel contents, yet you also said
"The fuel issue is totally separate"

genuinely interested, not being picky.

 

Topcat47

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The only parts "lubricated" by the fuel are the HP fuel pump(s) and the injector(s). Low sulphur diesel is an attempt to reduce acidic polution in the atmosphere. I know people who add a small amount of 2T oil to the diesel to compensate for the perceived lack of lubricity caused by the reduced sulphur. I am not one, nor have I experienced any particular problem with my 1GM10 that could be traced to low sulphur diesel. I only used CF4 mineral oil these days and 15-40 seems to be the default rather than the 20-50 beloved of my old bangers.
 

winsbury

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This is worth a read : http://www.canalworld.net/forums/index.php?showtopic=77731

As far as I can tell from this and other threads there is a lot of divided opinion, on my own boat there is two separate cans of oil from the previous owner, one for engine and one for gearbox but neither is in the original can so goodness only knows what is in them.

Even Morris' website doesn't state the API ratings for their mono-grade oils so have asked their advice too. What they do state online though is that filtration has a bearing on suspended particular matter either being filtered or being allowed to settle in the sump too, with mono grade oils using the less sophisticated sump and strainer method whereas the Bukh has a proper oil filter. Yet another anomoly !

I'm awaiting Bukh's official answer on this and will publish it here when I get it.
 

vyv_cox

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There has been a similar discussion about air cooled VW engines, the manuals still recommend monograde but I know of no convincing reason why a multigrade is not better. The vast majority of VW owners use multigrades, I did for years and years, never a problem.
 

winsbury

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So, here are the replies from Bukh and Morris:

Morris Lubricants: I would recommend a product now called Golden Film SAE 30 for this application which is slightly thicker but will give you an API of CC.

Bukh: the engine and gearbox any 15W40 mineral oil that is suitable for heavy duty diesel engines will be fine.

they also attached a table for the current engines:

bukh oil.jpg
 

RichardS

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So, here are the replies from Bukh and Morris:

Morris Lubricants: I would recommend a product now called Golden Film SAE 30 for this application which is slightly thicker but will give you an API of CC.

Bukh: the engine and gearbox any 15W40 mineral oil that is suitable for heavy duty diesel engines will be fine.

they also attached a table for the current engines:

View attachment 59695

I agree with Vyv's post #12 and would go with the Bukh advice and use a 15W-40 multigrade. The cheap supermarket stuff (Lidl, B&Q etc) will be fine if you are changing it annually.

Richard
 

RobBrown

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Pretty sure recommended oil in my original Bukh DV20 manual (1982 vintage) says SAE20 CC for both gearbox and engine. 20 is now rare, so I use HD30 for older diesels, which is readily obtainable from high st car parts shops eg Carlube products.
 
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