Mixing synthetic and mineral oil

penfold said:
Going by the vessel in the OP's profile, it will be a single phase genny of perhaps 20KVA, so more or less as you describe.
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Yes just looked at the OP's profile likely an Onan, if so has three or four jug Kubota. If he is having to top up lube between services I would be seriously concerned. However seems to want to plough on regardless.

However none so deaf as those who do not want to listen................
 
jimbaerselman said:
Slight oversimplification follows -

How the specification is achieved is irrelevant. Mineral oil, vegetable oil, synthetics - any could be used interchangebly, or mixed, as long as they meet the spec.
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The over-simplification is that synthetics are used in "higher spec" oils.

Higher spec here means they are designed for more extreme temperatures, and contain additives to handle that. Older and simpler engines run cooler, and do not need this extra expense. There is also much anecdote that lubricants designed for hotter engines cause greater wear when used in cooler running engines.
 
Whats the cost of your engines and what is the cost of making sure you have the right oil. I would change it just to be sure.
 
I think people may have got the impression that I am anti synthetic lubes, which is not true at all. As other posters have commented I am more than obsessed with just using the correct spec for the job amd adhering 100% to manufacturers oil drain intervals.

Many years ago I was asked to investigate lube oil consumption issues on a number of Cummins C Series powered gen sets. Turned out that operator had a mix of Mercedes and Cummins power units in his generators. At the time the Mercedes motors required lube to MB Specification 228.3 which could only be satisfied by a 10W30 fully synthetic lubricant. The Cummins reqirement was a lube to their CES 2077 which was a 15W40 generally a mineral base stock although Mobil did formulate a synthetic lube to this spec. As the Mercedes spec lube was three times the cost of the Cummins lube operator 'perceived' that the MB synthetic lube was better. Only wanting to purchase one grade of lube the operator used the 228.3 lube in both the Cummins and the Mercedes motors.

Within 5,000 hours the high cost 228.3 10W30 synthetic had glazed the bores, spalled the cams, and also caused serious degree of overhead wear.

Life has now moved on and lubricant manufacturers produce lubes with very sexy additive packs which meet a whole raft of manufacturers specifications and ACEA were largely responsible for pulling all this stuff togther.

However lube compatabilitity is still important, our little Kubota motor requires a 15W40 lube to CJ-4, CI-4, CH-4. You can use 10W30 for low temperature operation.

My only concernbregarding synthetic lubes is driven by the fact that unless originally specified, at manufacturers lube intervals they do nothing for you other than cost extra $$. Trouble then starts when people start to extend their drain intervals to make the financials stack up.

We have no clue what diet OP has been feeding our little genny motor as we have not been told, however the sniffy response to the correct and good quality lube used by the servicing agents rings alam bells and we know is that it may have high blow by, as it requires topping up between servicing.

Finally when it come to topping up Mobil have always been clear that when mixing different lubes the additive pack in the higher specifiction lube oil may become destabilised when mixed, so best to be avoided.
 
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Latestarter1 said:
Yes just looked at the OP's profile likely an Onan, if so has three or four jug Kubota.
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OP's genset is an Onan MDKAZ, 1500rpm single phase 50Hz job, Kubota motor 4 pot, 1500cc, 4 litres of oil in it. Not a particularly stressed motor even when the full 11Kva is being taken.
 
Latestarter1 said:
Also do you run motor on the high dip stick mark?? Very common for boat owners to be over zelious with lube oil top ups and engine will want to burn off excess lube, staying between the two marks can reduce top ups.
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That's very interesting. I have a Yanmar 2GM20 in my little yacht, and I've been noticing what I thought was increased oil consumption lately. That is, I never used to bother to check all that often, but after a long hard run I had a look and found it down towards half. Filled it up to the top, and now look more often, and often find it back on half.

I assumed it was using oil and would keep running down if I wasn't topping it up, but you're suggesting maybe it "wants" to be on halfway and if I don't put more in it might stop there and not go any lower?

Cheers

Pete
 
prv said:
That's very interesting. I have a Yanmar 2GM20 in my little yacht, and I've been noticing what I thought was increased oil consumption lately. That is, I never used to bother to check all that often, but after a long hard run I had a look and found it down towards half. Filled it up to the top, and now look more often, and often find it back on half.

I assumed it was using oil and would keep running down if I wasn't topping it up, but you're suggesting maybe it "wants" to be on halfway and if I don't put more in it might stop there and not go any lower?

Cheers

Pete
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Small motors have pre calibrated-dip sticks and installation angles can be all over the place.

I would check the actual amount of lube you have in your pan and filter against the engine data sheet next time you service. Once filled with calibrated quantity of lube keep an eye on it. There may come a point where level stays constant and finds its own level between the two marks.

Owners can often be a little 'ainal' over checking lube levels and adding top up lube.

Good luck
 
Latestarter1 said:
However seems to want to plough on regardless.

However none so deaf as those who do not want to listen................
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err.... I asked a question about it on here, and followed the advice given. Not "ploughing on regardless" involves cancelling my family holiday and staying in port waiting for a service engineer to arrive. To be honest, time on the boat with family is precious and i'd rather risk blowing up the genny.

Anyway, thanks for the advice, I have no doubt it's technically correct as ever.
 
Nick_H said:
err.... I asked a question about it on here, and followed the advice given. Not "ploughing on regardless" involves cancelling my family holiday and staying in port waiting for a service engineer to arrive. To be honest, time on the boat with family is precious and i'd rather risk blowing up the genny.

Anyway, thanks for the advice, I have no doubt it's technically correct as ever.
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My response to your post was some valid questions and helpful pointers regarding your genny were and are still are being completely ignored which is why I made the comment 'ploughing on regardless'.

What I sense are are some minor issues quickly turning into major expensive poo.

Unlike the S of F this advice comes free.....
 
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Latestarter, apologies i'm on a flaky 2G connection and had completely missed your post #10, which does indeed ask pertinent questions and give good advice.

I'm convinced there is an issue with the genny, but have had it checked 3 times now and it keeps getting the all clear. Symptoms are:

End of last year it started vibrating more than usual, and when I switched it off it spat a load of soot/oil into the water. This was put down to service agent overfilling with oil, even though it had run 200 hrs since the oil change, but was told no damage had been done.

After this years service impeller failed after 10 hours, put down to blockage over inlet, so probably unrelated

In use this year after approx 40 hours running since service, it started cutting out with only moderate load. Checked by engineer and no fault found, and seemed to right itself.

During charter the skipper reported that it suddenly lost oil, but he reported this on the day I picked the boat up for our family holiday. Try getting a service agent to St Tropez at short notice in mid August, so I had no choice but to set off without engineer checking again. By this time genny had run approx 200 hours since service, and most of this time with just one a/c unit running, which client insists on.

I then started this thread as I couldn't contact the service engineer, and checked the oil daily, and it doesn't seem to be dropping any further, but as it was well below bottom mark of dipstick, and based on advice on the post (and missing your post #10), I added half a litre of semi-synthetic.

Has since run OK for 30 hrs approx, although still does cut out at under 40 amps, which i'd have thought it could handle?

Of course i'll have it checked again when I get back from this cruise, and have oil changed as it is now mixed.
 
Nick_H said:
err.... I asked a question about it on here, and followed the advice given. Not "ploughing on regardless" involves cancelling my family holiday and staying in port waiting for a service engineer to arrive. To be honest, time on the boat with family is precious and i'd rather risk blowing up the genny.

Anyway, thanks for the advice, I have no doubt it's technically correct as ever.
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Much more interestingly, and for the benefit of those of us currently stuck at our desks (in my case, designing staircases...) in what lovely anchorage are you posting from ce soir?

Cheers
Jimmy
 
What's happening at 40amps? You say "cut out". Is the electrical breaker tripping or the engine stalling? If former, then nowt wrong with engine. If latter, as I guess is the case, the engine isn't making enough torque and power to generate 40amps so is only making roughly 9kw not the correct 12-13kw that it can develop. (It's an 11kva genset nominally). So the engoine is off colour somewhat.

Just to eliminate one thing, make sure it is failing to do 40amps with a cold air supply ie before engines hot or with lid open. Gensets (esp non tubo/intercooled like yours) in hot engine room can stall at 80% of full load just becuase of sucking in 80deg C ambient air so there isn't enough mix to develop full power

Jimmy, I'm also at my home desk with drawing board out, designing staircases :-)
 
jimmy_the_builder said:
Much more interestingly, and for the benefit of those of us currently stuck at our desks (in my case, designing staircases...) in what lovely anchorage are you posting from ce soir?

Cheers
Jimmy
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We're currently anchored with long line ashore in Calanque de Morgiou, near Cassis. Found a lovely anchorage yesterday on N side of Ile Riou, proper sand and shallow clear water. This is a beautiful stretch of coastline, I can see why BartW likes it so much. We haven't been in port for a week, 'cept a quick stop for fuel and water, but looks like there may be a bit of wind tomorrow, so will be trying La Ciotat, Bandol, or Sanary-sur-Mer as we could do with a day in port for general housekeeping reasons.
 
jfm said:
What's happening at 40amps? You say "cut out". Is the electrical breaker tripping or the engine stalling?
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Actually both, although I think the trip was down to genuine overloading, but it does stall from time to time at <40 amps. Interesting point about ambient heat though, as i'd say it happens mostly when stationary (with engine blowers off) after a run, so it could be drawing hot ambient air from engine room. I'll do some trials.
 
If it is a Onan? the first thing you need to do is see what fault code it flashes up on the start/stop switch when it stops. this will give you the reason it has stopped. Fault codes are in the back of the operators manual.

If you don't have the manual?PM me and I will email you one.

You can find the last fault code in the history - you need to do the following.

With generator not running,
Press and hold stop until switch light comes on
Press stop 3 times
The light will then flash either once, twice, three times, four times or Seven
This is repeated for a couple of minutes.
If it show's a fault code 3, you need to press stop once more.
It will flash a two digit code, like 1 flash short gap 6 flashes.
this will be code 16.

The Onan derate for high air temperture is 1% for every 5.5C above 27C, with a maximum of 50C. So the max derate will be around 5%.

I hope this helps

Anthony
 
Anthony, thanks for that data. Please can you explain a bit more what you mean by "de-rate" and "max 50deg C"? Do you mean that naturally the engine produces less power 1% for every 5.5deg? In otherwords, the engines sensors know the quantity of air going in at WOT and the ECU naturally supplies less fuel becuase of the less dense air? Or are you saying the software measures the temperature and actually de-rates the engine via the ECU? (which is somewhat the same thing i suppose...)

I'm currently speccing a new boat and need to overcome this problem. On my last boat I had 2x 22.5kw Onan gensets (built 2010), with the 3.3 litre engine. Should be good for 85+ amps each and they were if in a cold engine room or with the engine fans running. But if I ran the boat then anchored, the e/r temp rose to 80deg (due to 6 tonnes of caterpillar cast iron at that temp) and the gensets engines would stall, not trip, at 60 amps, which is more like 20% derated compared with your stated 5%. For the hour before a meal when there is full on cooking in the galley, plus normal overhead of zero speed stabs and airco plus the 24v charger load, I needed around 75 amps to run the boat at anchor, so this was quite a nuisance (becuase i prefer not to run 2 gensets if possible).

Same effect occured on both gensets, so not a fault with one of them i think. I therefore put this down to hot intake air

Next boat, just going into build now, will have 2x 27kw (which is the same 3.3litre engine and just a bigger alternator). I plan to have ducted air, with switchable continuously rated fan, drawing outside air at say 27degrees (Mediterranean) and blasting it onto the face of the genset where the air intake is. Hence the genset will mostly breath air at 30deg. Does this make sense to Latestarter/you/other engine nuts on this forum please?

Thanks
 
jfm said:
blasting it onto the face of the genset where the air intake is. Hence the genset will mostly breath air at 30deg. Does this make sense to Latestarter/you/other engine nuts on this forum please?

Thanks
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Dont they already have water cooled air coolers fitted , couldnt one be added or beefed up , you would expect the manufacturers would help out knowing they would be creating a more useful product to attract wider market ?
 
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