Oil changes

[jimi]

On TCM's recommendation I've taken to changing the engine oil ever 6 weeks or so (no problem with the Pela oil extractor) and the engine certainly seems to be running very smoothly. Question is .. if I'm changing it frequently then presumably the oil grade is a lot less relevant... thoughts?

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[Richard_Blake]

I'm interested in this one too. I assume you mean the "SAE 20-40" kind of grade, and not just quality.
As I understood it from a real, and rather mature mechanic, the SAE or equivalent grade is recommended by the engine maker who knows the range of temperatures the various inside bits of your engine tend to run at, which apparently can be very different from each other, and secondarily refers to the range of ambient temperatures you're going to be going boating in. So I don't see that changing it more often would make the grade less important. He also said that if you don't use the engine for periods of more than a week or two, it is very important to use the best stuff you can get, because there'll be fewer problems with sludge collection in sump or small passages, and less risk of acids or something building up. I'm quoting here, not speaking from expertise. Hope some experts pick this one up.
Cheers
Richard

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[Robin]

Which does he sell, the extractors or the oils?

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[Avocet]

Just as a thought, how many engines die from lubrication problems anyway? I've never done anything special for mine (rather neglected it on occasions in fact) and the bottom end seems fine. The bit that seems to kill off engines like mine is corrosion in the cylinder head (raw water cooled). I'm not sure I want my bearings to last 200 years if the head has had it after 15!

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[BarryH]

Nah thats a load of nuts. Using cheap oil is the downfall of many an engine. My brother changed the oil in his car every 1500 miles using a cheapo oil. The engine died in a year. Buggered rings and main bearings. That was a petrol. In diesel oils there's a build up of acids from the combustion. This will attack the white metal of the bearings if left for long periods.

The life blood of any engine is good qwality clean oil. More freaquent changes is good, but six weeks! How many hours will the engine run in six weeks. I do mine 3 times a season, but then I'm a stinkie and the boat gets used a lot.

Do a search on mobo for "oil filters" In one of the posts thers a link to a site comparing oil filters of different manufacturers and the comparison of each. I've found that Purelator filters are good in as much as the filtration surface area is roughly 25% bigger than a lot of the mainstream filters, allowing a finer filter but not reducing the flow rate.

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[jimi]

I have adhered to the SAE ratings but I really do'nt understand what they mean, it was more the CD/CF type classification I was worried about. I have'nt used cheapo oils just mid range one's and quite seriously when I started doing it you could have tarred your drive with the stuff that was extracted. Perhaps in a saily boat when you tend to switch the engine on and off the lubrication as far as engine wear goes may be more important. I was told that 90% of engine wear happened during the ignition period?

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[Robin]

Actually we had a Mercedes on our last boat that died (seized) when the oil pump drive sheared, it was a new pump fitted 800hrs before on a complete rebuild. That was a mechanical failure though really, not a lubrication break down.



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[Heckler]

i suppose id better put my 2 penworth in, sigh,

use the sae grade that the manufacturer recommends, thats it, so VP 2030 = 15/40 (if i remember right) diesel formulated. as long as the engine is run on a regular basis AND got to temp quickly, no point in putting anything better in such as synthetic or semi etc. if used regularly change at the intervals recommended by the manufacturer, usually 150 hrs or yearly, dont see the point of changing every six weeks just for the sake of it, and changing it that regularly doesnt make it run smoother, we run in a very good engine enviroment from one respect, nice clean air, but the bad part of course is that a lot of marine engines run to cool for much of the time and that allows water (emulsion) and acid build up in the oil.
to sum up do what the manufacturer says, nothing more nothing less unless you are in a very unusual situation and then adjust accordingly
in africa we used to change the genny oils (hot, dusty, 135 kva CATs) and filters every week, we had 3 in a row and used to rotate them weekly, stripped them after 3 years, could have run them for another 3 years except for the rear oil seals had worn out.
the land rovers and toyotas did 200,000 clicks and the chassis corroded away before we touched the engines, we used to change oil and filters every 5000 clicks,
stu



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[Robin]

Jimi

IMHO follow the handbook and pick the grade it says and the usual SAE rating is 15w-40, use a good quality oil from a major oil company or even the engine makers own, on a sailboat engine you are nor going to break the bank doing it.
Change the oil and filter as the handbook says after 'n' hours and at the end of the season for winter lay-up. Diesel oils tend to go black in use, that shows the oil is doing it's job. When you use the engine, don't run it light, ie not for charging batteries unless in gear under way or at least in berth in gear. Once started it is best to run the engine to normal temp before shutting it off to sail. Best is to start up just before you are ready to leave, warm up whilst running at normal revs in gear on way out of harbour, then shut down and sail.



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[jimi]

But surely you can't do any harm by changing more frequently with potential benefits to the engine? My thought was that as you say, on a saily boat, the engin rarely has time to get to temperature. You switch it on and then berth. On the other hand there might be days when you run it hard for a few hours when motorsailing with the kiddies shouting "Are we nearlyy there yet?". So presumably the lubrication in the engine does have a fairly wide range it needs to operate over?

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[Johnjo]

Should imagine its all to do with how you use the engine,
If your based on the coast and only use your engine to get in and out of a marina and
the engine never really reaches its correct operating temperature its never going to get hot enough to boil
off any condensation which forms in it.
Resulting IMHO more oil changes needed.

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[Johnjo]

sorry jimi did not realise you just said that!........

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[tcm]

Re: Oil experts required

Forgotten when i blitherd on about this. But there seems hardly any solid information about oil changes. Most engineering equipment is sold to people who would prefer there to be fewer oil changes. And if they can get away with even fewer than that, so much the better.

But when you change oil in a diesel, the oil is black. It "needs changing". So when does this happen? It can't be like a light bulb, which always works just as well as it did on day 1 and then suddenly doesn't. It must be gradual. But nobody tells us how the oil deteriorates, whether linearly, or otherwise. Either way, if it needs changing after 12 months, then wouldn't it surely be better after 6 months? Or if it needs changing after 100 hours, surely much better after 25?

My only relevant exp is with motorcycle engines, and i belive the issue most relevant to new engines, not old. instead of chaging every 5000 or so miles, someone reported amazing mpg from 25,000 miles engine as a result of changing the oil much more frequently esp in the early life of the engine. Amazing such as 20-30% more mpg. Of course, i am always wary of gits claimig massive mileage co they don't rip away frm the lights and so on. But with a new engine i also changed oil v frequently, and also got amazing mileage, unable to do as badly as the listed mpg no matter how hard i tried.




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[Robin]

Re: Oil experts required

I fiited a new engine in our last boat, Volvo MD22L 50hp (I know it's a tiddler). This engine started life as a Montego van diesel, was marinised by Perkins as Prima 50hp (had their label even) and then was painted green by Volvo who added their gearbox (and another label saying Volvo MD22L).

Montego service interval 6,000mls (assumed, I don't drive one)
Perkins service interval 400hrs, using oils from all major companies as recommended
Volvo service interval 200hrs using Volvo own 'special' oil to avoid invalidating the 3 yr warranty. (Volvo oil seemed to be relabelled BP)

IMHO changing the oil at the recommended interval will be OK, they take into account the vagaries of marine (even sailyboat) use and cover their backsides too. More frequent changes will do no harm except to the wallet.



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[david_e]

Re: Oil experts required

Re: Motorbikes - it would depend on what make, Triumph/BSA etc leaked so much that changing was hardly neccessary. High reving Honda 4 stroke, wiser to change regularly, but in line with service intervals. My pop was a Honda dealer for dozens of years - never used Honda oil unless customer specified it - too expensive and same as Castrol/Silkolene etc - but would always put fresh oil in if in doubt when buying and reselling a used bike.

My Volvo 3 pot is due a change next month, a year and 60 hours on, probably needs it looking at the blackness of it, seemsto run OK.

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[DeeGee]

For the detail of all this, you may be interested/bewildered by http://www.wearcheck.com/literature/techdoc/WZA007.htm It is NOT a child's guide, but worth reading carefully.

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[DeeGee]

We need Luther.

http://www.go-synthetic.com/409_000_Mack/409_000_mack.htm

Here's another one for your album!!

Maybe the answer is some simple tests for yourself. The oil will have deteriorated when the viscosity falls too low, or too high. Extract some oil, and put something like a chinese chopstick in it, ditto to the same extent in some fresh oil. See how the oil runs off by eyeball. I expect that will be pooh-pooh'd by the pundits. Where is Luther??

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[bedouin]

Re: We need Luther.

He's about somewhere, nearer home than usual, but he's probably a bit busy at the moment.

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[jimi]

Many thanks, a very informative site!

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[DeeGee]

Nice explanation here...

http://www.chris-longhurst.com/carbibles/index.html?menu.html&engineoil_bible.html

<hr width=100% size=1>Black Sugar - the sweetest of all