I'm assuming the wear index in fig 8 indicates less wear as the figure rises, or have i got that the wrong way round.
quote from the text
''Synthetic oil outperformed semi-synthetic and mineral oil, as the metal wear values decreased for the synthetic oil compared to the semi-synthetic and mineral oil in different proportions for each of the wear metals studied.''
total waste of testing on modern engines and even manufacturers know that short oil change intervals around 5k 6k mark are best for longevity of an engine (not that its admitted ) but most mechanics I know will try and get customers to change oil at half interval something Ive done for many years
with modern gdi engines as we know the carbon build up using the wrong oit will wreck an engine fairly quickly so recommended oil is best used to prevent it, I think there is a new oil which keeps parts clean and dirt free so may be worth the extra in keeping using that,
though not needed on the older port injection engines
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total waste of testing on modern engines and even manufacturers know that short oil change intervals around 5k 6k mark are best for longevity of an engine (not that its admitted )..
If one could somehow know the test results without doing the testing, I suppose the testing would be a waste of time.
But one can't
OTOH largely ignoring your test results in favour of recieved opinion, as these authors appear to do, is a bit of a waste, but at least they do present the unpalatable results
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I'm assuming the wear index in fig 8 indicates less wear as the figure rises, or have i got that the wrong way round.
quote from the text
''Synthetic oil outperformed semi-synthetic and mineral oil, as the metal wear values the decreased for the synthetic oil compared to the semi-synthetic and mineral oil in different proportions for each of the wear metals studied.''
Nope. Thats why I mentioned that the index isn't one of those that work backwards.
I believe its a measure of the effect of the total ferrous metal in the oil on a magnetic field, but it isn't calibrated, and thus can;t be expressed, in terms of mgs/L of Fe, so its just a unitless index number, plus it misses non-ferrous wear metals like copper and lead from bearings.
It does, however include the effect of large particles, which are believed to be the more significant measures of wear and predictors of failure.
The commonly reported elemental analysis misses these, because the spectroscopy method used only detects tiny (can't remember the cutoff though 3 microns rings a bell) particles unless you acid digest the sample. By those measures, the same paper shows slightly lower wear metal levels for synthetic oil, and those are the measures they choose to stress, (as per your quote) but those measures are flawed.
The PQ wear index is the better measure, and in this case shows consistently higher wear for synthetic oil.
Dunno if its significant but it, and the authors emphasis, is sort of interesting. Of course without replication it could just be chance variation in the stress response of the gensets, but I suppose they cant very well say that without undermining the paper.
Doing it in triplicate you'd need to buy, run and analyse 9 gensets, pricier and it might not be enough. You'd have to do statistics on the results, and you run the risk of getting statistically insignificant differences. which can be hard to get published.
Shouldn't be, of course, but they are.
Edited by edlithgow on 01/03/2025 at 02:30
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Not having read what you are talking about, surely having an oil analysis done would tell you what you really need to know, have you checked out the motor oil geek on Youtube whom you could send an email and ask him as he is an oil expert and may possibly answer your question
but you may find this interesting It's SCIENCE, Not SPECULATION... just one of many videos
Edited by Bolt on 01/03/2025 at 09:27
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I didn't ask a question
Might have a look,thanks but generally I find Youtube video's unsuitable for conveying/acquiring research results, which might be why they aren't generally part of the established peer review process.
EDIT
OK, I HAVE seen one of his video's, Nothing to do with the present topic,of course, but it was claimed to provide some evidence of,oil having a shelf life (which I was otherwise pretty solidly convinced it didn't) and, knock me dahn wiv a fevva, there did seem to be something in it, though, partly because it was a Youtube video, it wasn't clear exactly what.
youtu.be/QeNLVUdoBU0
These were some very old and abused oils, which seemed to have been exposed to low temperatures in storage, and no experimental control was really possible. Comparing a new oil, as was done, isn't strictly valid, since the formulation certainly will have changed. Better alternatives might be comparing carefully stored old oil (which probably wont be available) or comparing the results of standardised ASTMS tests run on the oil when it was produced, which probably wont be available either, though they might be in a (probably secret) archive somewhere.
This seems particularly a problem when interpreting the oxidation numbers, when a comparable control is fairly necessary.
PLUS an hour of Youtube (skipping the Heavy Metal instrumental breaks) for a 2 minute lab report which would provide a lot more detail really isn't very efficient
Edited by edlithgow on 01/03/2025 at 14:54
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Interesting. They appear to have used small motorbike/lawnmower engines. Doesn't say what the blocks were made of, or whether or not they had liners. They have measured only iron, copper and chromium wear. What about aluminium? Also, they ran them for 1500hrs. This is much longer and in stages 2 and 3 much more arduously than most people treat their engines. Assuming an average speed of c34mph, that equates to c50,000 miles. The stage three test, where most of the wear took place, would never be inflicted on a modern mundane car engine, unless it was an old fully loaded 2CV driving up and down alps.
It seems to me that for an unstressed engine used lightly there's b***** all between the three types of oil. So perhaps it only needs to be changed every 50,000 miles these days? And as there seems little difference between them, apart from when under heavy load, if you don't need the engine to last longer than, say 200,000 miles, why buy expensive oil? (Unless you have a BIO engine:-/
Edited by John F on 01/03/2025 at 17:32
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I havn't attempted to equate this genset stress test to normal car engine service, and am unclear to what extent that would be possible, though its clearly easier and cheaper to run a reproducible test load regime with a genset than it is with a car.
I suppose "not much difference between them" would be a fairly unsurprising conclusion (though it isn't the general conclusion that the authors choose). Certainly I've never seen any reason to use synthetic oil in any of my vehicles.
The (largely ignored) fact that the synthetic oil gives consistently worse wear results under stress would probably surprise a lot of people though, especially if this turned out to be a reproducible result, and even more so if it turned out to be a generalisable result.
But we'd probably never know, since the industry would have no interest in telling us.
Edited by edlithgow on 01/03/2025 at 23:28
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The (largely ignored) fact that the synthetic oil gives consistently worse wear results under stress would probably surprise a lot of people though, especially if this turned out to be a reproducible result, and even more so if it turned out to be a generalisable result.
But we'd probably never know, since the industry would have no interest in telling us.
Yes, it surprised me. As did the similarity of mineral and semi-synthetic results in the earlier stages. Perhaps racing cars should use mineral oil! But fully synthetic was consistently best in the 'easy' stage 1 (using 50% of power constantly). However, even this stage was far more stress than most mundane car engines of 100bhp and above experience if driven calmly. Only around 40bhp is needed to cruise at 70mph and less than this for suburban journeys.
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But fully synthetic was consistently best in the 'easy' stage 1 (using 50% of power constantly). However, even this stage was far more stress than most mundane car engines of 100bhp and above experience if driven calmly. Only around 40bhp is needed to cruise at 70mph and less than this for suburban journeys.
Well stress probably isnt just power output. I'd guess a steady 50% of rating could be less stressful than a variable load averaging much less, which is probably what you get driving in traffic
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What about aluminium?
I didn't think any engines had aluminium wearing surfaces ? If so they wouldn't last long. Alloy blocks always have liners, don't they ?
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What about aluminium?
I didn't think any engines had aluminium wearing surfaces ? If so they wouldn't last long. Alloy blocks always have liners, don't they ?
Pistons?
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I didn't think any engines had aluminium wearing surfaces ?
OHC aluminium heads. Camshaft bearings? I know Lotus used to run camshafts directly in the ally.
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I didn't think any engines had aluminium wearing surfaces ?
OHC aluminium heads. Camshaft bearings? I know Lotus used to run camshafts directly in the ally.
Aluminium heads, OK, but do they have 'wearing' surfaces ? Wouldn't be any good for valve seats, would it ?
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I didn't think any engines had aluminium wearing surfaces ?
OHC aluminium heads. Camshaft bearings? I know Lotus used to run camshafts directly in the ally.
Lotus twin cam heads had replaceable shell type bearings. Still widely available as are virtually all parts for that engine.
On the other hand the 2 litre Zetec in my Caterham has cams that run directly in the alloy. But machining practices and materials available in the late 90's/early 0's were way better than Lotus had to work with in the early 60's.
I have stripped a couple of "sc***" examples of these engines in the past and one had been to the moon but there was no visible wear to the cam journals. Some of that engine is still under my bench as a "just in case" spare. Its built from the best of a collection of parts I had and ran perfectly for a couple of months while I built the current engine. Made about 155 bhp using mostly used and all totally standard Ford engine parts. I did splash out on a set of new crank bearings.
And lets not forget that the lubricants available today are a world apart from the stuff 60 years ago.
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And lets not forget that the lubricants available today are a world apart from the stuff 60 years ago.
As long as its not synthetic, apparently
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What about aluminium?
I didn't think any engines had aluminium wearing surfaces ? If so they wouldn't last long. Alloy blocks always have liners, don't they ?
Didn't BMW have wear problems a few years back with alloy blocks, possibly with a surface treatment of the cylinder bores?
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What about aluminium?
I didn't think any engines had aluminium wearing surfaces ? If so they wouldn't last long. Alloy blocks always have liners, don't they ?
Didn't BMW have wear problems a few years back with alloy blocks, possibly with a surface treatment of the cylinder bores?
Nikasil coating was the issue. But I seem to remember it was something in some UK petrol that the Germans did not have that caused the issue.
Pretty sure they went back to steel liners.
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What about aluminium?
I didn't think any engines had aluminium wearing surfaces ? If so they wouldn't last long. Alloy blocks always have liners, don't they ?
Not necessarily.
Didn't BMW have wear problems a few years back with alloy blocks, possibly with a surface treatment of the cylinder bores?
Nikasil coating was the issue. But I seem to remember it was something in some UK petrol that the Germans did not have that caused the issue.
Pretty sure they went back to steel liners.
Liners could be problematic as well - e.g.Jaguar
Better to use a top quality aluminium alloy, e.g. VW's reliable W12. Here is an extract from VAG's self study program SSP 267.....
The cylinder block is cast from a hyper-eutectic aluminium silicon alloy (Alusil). Solidification of the Alusil melt yields pure silicon crystals and aluminium silicon mixed crystals. A special manufacturing process employed when honing the cylinder contact surfaces exposes the separated silicon crystals. This production process creates wear-resistant cylinder contact surfaces, thus obviating the need for additional liners.
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<< The cylinder block is cast from a hyper-eutectic aluminium silicon alloy (Alusil). Solidification of the Alusil melt yields pure silicon crystals and aluminium silicon mixed crystals. A special manufacturing process employed when honing the cylinder contact surfaces exposes the separated silicon crystals. >>
That's interesting. Is anyone a trained metallurgist here ? I wonder how the various costs balance against performance ?
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<< The cylinder block is cast from a hyper-eutectic aluminium silicon alloy (Alusil). Solidification of the Alusil melt yields pure silicon crystals and aluminium silicon mixed crystals. A special manufacturing process employed when honing the cylinder contact surfaces exposes the separated silicon crystals. >>
That's interesting. Is anyone a trained metallurgist here ? I wonder how the various costs balance against performance ?
Silicon crystals are apparently 120 to 150 Rockwell F, on the Moh's scale of hardness it is rated 7, which is the same as quartz.
This suggests if anything is going to wear it would be pistons / piston rings rather than the cylinder bore surface
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<< The cylinder block is cast from a hyper-eutectic aluminium silicon alloy (Alusil). Solidification of the Alusil melt yields pure silicon crystals and aluminium silicon mixed crystals. A special manufacturing process employed when honing the cylinder contact surfaces exposes the separated silicon crystals. >>
That's interesting. Is anyone a trained metallurgist here ? I wonder how the various costs balance against performance ?
VW Group's W12 wasn't built down to a price.
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