Engine oil replacement period

[BobnLesley]

We have a thirty odd year old Volvo MD6Aand in accordance with the handbook, I change engine oil every 50 hours and then oil+filter every 100 hours. I have recently been advised, that due to the improvements in oil technology since the handbook was published, I really don't need the intermediate oil changes? Any opinions would be appreciated.

 

[webcraft]

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A lot of people reckon you shouldn't use modern high-spec oils anyway as the additives are bad for old marine diesels.

50 hours is equivalent to about 2,000 miles in a truck or van engine, which seems a little excessive. 100 hours or every season for oil and filter is probably about right - it is what we roughly base ours on now with the replacement Beta, although we are not religious about it. Personally I woujld never change the oil without changing the filter, especially on an older engine.

(Getting rid of our MD6a was a happy day - do you still have the 'Combi' instead of a gearbox, and a dynastart?)

- W

 

[Refueler]

If you use cheapo supermarket oil then I would change as per book. Mainly because cheap oil is allowed to use x% recon oil. This is not bad as some may say - as we generally do not use high performance engines in boats.

If you use expensive major oil co. brand name oil - then yes - technology has moved on and they may contain detergents and special additives to 'wash' systems. High performance engines are best served by these along with turbo jobs. But for general 'donks' IMHO overkill.

I have a personal dislike of detergent containing oils so prefer cheap to middle road oils that do not 'froth up' ... I also believe that more basic oils are better in our generally cooler running boat engines than fancy stuff - no real reason for it - just have gut feeling about it.

I would never use synthetic in a boat engine unless specifically detailed by engine manufacturer and also never mix synthetic and mineral when topping up. Some synthetics cause mineral oil to clag up. They never tell you that !

Boat diesels - IMHO - bog standard mineral oil, no additives ... cheap cr*p change as per book, middle road recognised brand you can run much longer .....

To give an idea of how long I pushed my engine : Perkins 4-107. Engineer who fitted it used reasonable 10 - 40W diesel spec oil. Nearly 5 yrs later I changed the oil and filters. Filter was near finished, but oil was still in spec ! ( I do have a fuel lab !! /forums/images/graemlins/grin.gif ).... yes it was black but Viscosity, Alkalis and Acids, Moisture were still in spec., only item that was borderline was sediments - to be expected. I never told lab how old it was till after.

Please note that above is MY opinion and MY method and is NOT based on lab experience or industry data. If you are concerned about engine life - do as manufacturer advises.

 

[dulcibella]

Suggest every 100 hours at least, plus a change before laying up or any non-use exceeding a month or so.

 

[webcraft]

[ QUOTE ]
Suggest every 100 hours at least, plus a change before laying up or any non-use exceeding a month or so.

[/ QUOTE ]
This strikes me as both impractical and unnecessary. Why do you need to change the oil just because the engine is not being used for a month? I have never heard of any manufacturer recommending that.

Most modern marine diesels were originally designed for trucks, dumpers etc or to run as generators for hundreds of hours with little or no maintenance.

I think Nigel's post above about 5 year old oil still being in spec backs up my view.

Of course, to a certain extent it depends on whether or not you prefer sailing to maintenance . . .

- W

 

[brianhumber]

Would absolutely agree with Refueller. My oil also lasts c5years and is still in spec.
A lot a clap trap is still written by people about oil changes and their conviction that engines will disappear before your very eyes due to acid oil if you do not change oil every autumn, they are simply repeating what they have read not what they know and the fact manufacturers have to allow for engines operating in jungles, deserts and tundra where conditions are far far more exacting than NW Europe.

Brian

 

[ShipsWoofy]

How do they recondition oil?

 

[Bilgediver]

Any opinions would be appreciated

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Unfortunately non of the advice you have received so far reflects your particular concern as per the engine in your boat.

You have an old Volvo Md engine where the manufacturer basis his recomendations not only based on the deterioration due to combustion but also and more importanly in your case also due to fuel dilution from the internally mounted fuel pumps.

Too many folk ignore this source of contamination which is similar to the spill from injectors however in the case of the pumps the leakage is to the sump. The pumps need leakage to lubricate and although minute it all adds up. You can actually smell the diesel in well used oil from these old diesels and if not replaced to schedule you run the risk of all sorts of unscheduled events such as engine runaway. Moreover the oil does not make a good lubricant when well diluted.

It doesn t matter wether it is Tesco's cheepest or Castrol gold plated , dilution is the main problem dictating oil change so exceed 100 hours at your peril.

PS Tesco's mineral for diesel is fine and less likely to cause glazed liners than CAstrol synthetic Magnetic bug digestive supa dupa Grade xxx

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[covenanter]

With an old engine more frequent changes with a cheap oil are better than longer periods with an expensive oil.

 

[Marsupial]

Well there you go, for the record

I HAVE SEEN BIG END AND MAIN BEARING SHELLS EATEN AWAY BY ACID IN AN ENGINE THAT WAS LAID UP WITH OLD OIL IN IT.

I conceed that this was before the days of positive crankcase ventilation but boat diesels are not that well ventilated and a damp running environment at low temperatures promotes acid residues.

In basic engines use a straight grade oil and change it regularly. Synthetics can be detrimental.

 

[Refueler]

[ QUOTE ]
How do they recondition oil?

[/ QUOTE ]

Recon oil ? We do not get involved in this as we work for suppliers of base oil intended for blending into over counter Lub Oil.
But basically it's filtered, cleaned and then various additives put in to help viscosity etc. There is nothing to stop a company using up to a certain % recon oil in a blend, the amount I am not sure of so will not quote a number.

It originally was developed as I'm told for haulage companys many years ago .... how true that is - I haven't a clue.

I do know brand names that have recon oil in, and one I actually used in UK .....