Detergents: Magnesium vs Calcium

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Originally Posted by SonofJoe
Molekule, I assume you're talking about this... https://www.anl.gov/article/nanoboric-acid-makes-motor-oil-more-slippery Are you absolutely, 100% sure this stuff is used in mainstream engine oils that are currently on shelves because I can easily imagine this stuff would fail at the first hurdle on any number of No Harm tests. Free acids, however feeble, in engine oils are always bad news!
i was referring to the various articles authored by researcher Erdemir, one of them being, "Solid Lubricants and Self-Lubricating Films," Handbook of Modern Tribology, CRC.
 
Wow. There is a lot in this paragraph that is pretty telling why LiquiMoly may have taken MoS2 out of its oils here... thanks for the paper reference, Mola... it's great reading!
Quote
In contrast, MoS2 and other transition-metal dichalchogenides work best in vacuum or dry running conditions, but degrade rather quickly in moist and oxidizing environments (Winer, 1967; Farr, 1975; Kanakia and Peterson, 1987). The friction coefficients of self-lubricating metal dichalcogenides are typically in the range of 0.002 to 0.05 in vacuum or dry and inert atmospheres, but increase rapidly to 0.2 in humid air. It is generally agreed that no solid can provide very low friction and wear, regardless of test environment and/or conditions.
emphasis mine
 
Originally Posted by SonofJoe
Any oil you buy already contains what might be described as 'ash'. The oil will contain just under 1% calcium carbonate (chalk) or magnesium carbonate (magnesite) in their mineral form. You won't be able to 'see' it because it will exist as tiny particles, colloidally held in suspension with organic detergent. These particles aren't abrasive because the only thing metal surfaces see of them are the long alkyl tails that surround each particle; not the mineral salt itself.
Amazing co-incidence...yesterday I was researching dispersents for keeping micronized solids in suspension in water, and came across the differentiator between stearic and ionic dispersents. stearic... https://www.researchgate.net/figure...contaminants-Dispersants_fig11_315655246 Just adding for comment.
 
This thread is great reading. It also lends to the idea that uoa's cannot tell everything about a oil. There are many compounds that are not included in the analysis. Thanks everyone for their contributions.
 
Originally Posted by PimTac
This thread is great reading. It also lends to the idea that uoa's cannot tell everything about a oil. There are many compounds that are not included in the analysis. Thanks everyone for their contributions.
I agree. I've learned a lot. This thread has gone above and beyond what I intended it to, and I'm soaking up every bit of it. The more indepth, the better. I've been googling and reading on this topic all day today.
 
Yeah, it's been good...I now understand the basis for the MgCa abrasiveness "wivestale" that I grew up with and the actual magnitude of the "issue"... Thanks all.
 
Hi everyone, Great thread! I also have a question. It concerns Boron (mentioned earlier in the thread) and more specifically its depletion in used oil. All of us have seen that when comparing Boron levels in VOAs and UOAs. For example - starting level of Boron in virgin oil can be 257 ppm, and after 6 500 km it drops to 164 ppm (or even less). What causes this depletion of Boron (what is the reason)? What happens with the Boron? Please excuse me if the question has already been answered in other thread.
 
Originally Posted by emod
Hi everyone, Great thread! I also have a question. It concerns Boron (mentioned earlier in the thread) and more specifically its depletion in used oil. All of us have seen that when comparing Boron levels in VOAs and UOAs. For example - starting level of Boron in virgin oil can be 257 ppm, and after 6 500 km it drops to 164 ppm (or even less). What causes this depletion of Boron (what is the reason)? What happens with the Boron? Please excuse me if the question has already been answered in other thread.
That's a really good question which I've never thought about before. I'm no Walter White but if I was to hazard a guess, it would be this... Boric acid is a white crystalline solid & a rather weak Lewis acid. In an ashless dispersant, it will be weakly bonded to one of the basic nitrogen groups in the polyamine part of the dispersant. It could be that over an OCI, stronger acids formed by fuel combustion or the oxidation of base oil both displace & replace the boric acid on the dispersant chain. Now boric acid, unlike most of the stuff you find in oil, is water soluble. You'll always get a bit of water in the sump from condensed blow-by gas (especially when the engine starts in cold conditions) & maybe the BA preferencially migrates into it. This would result in a net loss of Boron from the main body of oil. One thing I do know is that engine oil gets progressively LESS aggressive towards seals as it racks up the miles. This suggests that all dispersants get 'naturally' capped in the engine over time. So the acid displacement theory might be correct.
 
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Thank You SoJ, I may be wrong, but from the UOAs that I have seen it seems that the Boron depletion in diesel engines is "less" that this in gasoline engines. This somehow may be linked with your theory, since diesel generates more of soot and less of water during combustion (compared to gasoline), due to difference in the combustion type (as far as I know). Again, that's just a guess.
 
That's something I hadn't thought about before either. Thanks for bringing it up. Knowing now the role of "detergents" in oil, and the lack of abrasiveness, what additive, base oil, etc... is preferred when trying to clean out a dirty, sludged up engine? Do the detergents like Ca and Mg help break down sludge and carry it to the filter or do other additives fill that role? Are there no additives used that are designed for such a role? Are flushes and solvents like MMO the best option for such a scenario?
 
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Originally Posted by RDY4WAR
That's something I hadn't thought about before either. Thanks for bringing it up. Knowing now the role of "detergents" in oil, and the lack of abrasiveness, what additive, base oil, etc... is preferred when trying to clean out a dirty, sludged up engine? Do the detergents like Ca and Mg help break down sludge and carry it to the filter or do other additives fill that role? Are there no additives used that are designed for such a role? Are flushes and solvents like MMO the best option for such a scenario?
I'm probably going to upset a lot of people now by saying there in NO OIL ON EARTH that can clean out a properly dirty, long time sludged up engine! 100% of the work that you put into designing an engine oil is focused towards PREVENTING problems. Primarily you try to restrict the degree to which the oil oxidises because so many 'real-life' issues stem from this (out-of-control viscosity increase, corrosive metal loss, sludge deposition, etc). Under normal circumstances (ie API/ACEA/OEM testing) you put zero effort into thinking how an oil might 'correct' a severe problem, after the event. There are engine oils out there that claim 'clean-up' for advertising/product differentiation reasons. Invariably this uses a non-stardardised in-house test which you should always treat with caution. The test usually involves an engine 'dirty-up' phase (on a very bad oil) followed by a 'clean-up' phase on a new candidate oil. And yes, you can demonstrate a degree of sludge clean-up to support a claim. However, in viewing these results, you should bear in mind several things. During the 'dirty-up' phase, the deposition of sludge occurs over a few hours at the end-of-test. You purposely monitor this to stop it, before it gets too bad. You then, as quickly as possible, drain the dirty oil, add the new oil and restart the engine for the 'clean-up' phase. You typically find that 'clean-up' starts straight away. The flaw in this approach is that unlike in real-life, the relatively light coating of deposited sludge has no time to 'bake on' and compact down. This makes it relatively easy for the fresh candidate oil to remove what is relatively accessible, 'fresh' sludge. My guess is that oils don't have to be particularly special to 'clean-up' sludge in this way & any modern oil would do equally well. Ironically, as oils have improved & their ability to PREVENT problems has moved on by leaps & bounds, their ability to RECTIFY problems such as sludge has probably fallen off a cliff. If you're looking to resolublise sludge, what you chemically want are base oils rich in heavy aromatics & hetroatoms (Sulphur, Nitrogen & Oxygen). These are now absent in Group II & beyond. Ideally, to get rid of 'proper' sludge, you might give your engine a nice, long soak in hot Carbon Disulphide. However this might very well kill you, so kids, please don't try this at home! I sometimes muse about what would happen if you ran your sludged up engine on an oil based on Naphthenic base oil? Naphthenics have very low Viscosity Index & are hopelessly unstable. However they are very rich in aromatics so running one for say a week max (then dump & flush) might be something you could get away with. Alternatively (and this is strictly for the birds!) why not see what you could do with the 'extract' you get from Furfural Solvent Extraction (a process used to make Group I base oil). This is the grot that no-one wants but it's probably the perfect solvent for thick sludge!
 
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I'll back that...in order to drop out varnish and sludge, it has to be saturated with the stuff. Then once you know you have it, the fresh oil can only pick up so much of the already laid down deposit....if the sludge is really bad, does the new oil become saturated in the first few hundred miles ? No way to test that. I KNOW from turbine experience that the electrostatic varnish removers (electrostatic, works on polarity of the varnish molecules) will clean a system up with time (turbines run 8760 hours a year, not an hour or two a day), as the cleaned oil can pick up varnish every time around..rinse and repeat.
 
So which brand of oil is good to use to clean engine sludge did changing different brand of oil clean engine sludge?
 
I have an old truck that I inherited from my grandfather after he passed. It has 483k miles on it, and had been sitting for over 2 years before I got ahold of it. When I drained the old oil out, it was jet black and had the consistency of pancake batter. I put in PYB 10w-30 and let it idle for 15 minutes. Then I drained it and it came out black already. I put PYB back in and haven't messed with it since. I'm not sure if I should add a quart of MMO, let it run another 15 minutes, and dump again... or if there's a better oil for cleaning out such a situation.
 
Originally Posted by RDY4WAR
I have an old truck that I inherited from my grandfather after he passed. It has 483k miles on it, and had been sitting for over 2 years before I got ahold of it. When I drained the old oil out, it was jet black and had the consistency of pancake batter. I put in PYB 10w-30 and let it idle for 15 minutes. Then I drained it and it came out black already. I put PYB back in and haven't messed with it since. I'm not sure if I should add a quart of MMO, let it run another 15 minutes, and dump again... or if there's a better oil for cleaning out such a situation.
First off, don't worry about the oil being jet black. I'm fully aware that it worries folks in the US when it gets that bad but to me, an oil can be jet black and still be fully functional. Diesel oils can happily do HUGE extended drains and spend their entire life black. Second, don't worry about the 'pancake batter' appearance. It doesn't mean the engine has sludged. At a guess, there was a bit of dispersant VII in the old oil. It tends to impart a odd 'gloopiness' quality to the oil which can be a bit disconcerting the first time you see it. Third, be aware that when you do drain an oil, a lot of it can remain held up in the block. I once did an engine test (it might even have been a clean-up test) where I ran a full Ca-based oil, drained it & then added a full Mg-based oil. I was rather surprised afterwards to find so much Ca showing up in the newly added oil and back calculated that 20% of the original oil hadn't drained. I suspect the black 10W30 you drained was black because it intermingled with old undrained oil (not sludge). Had you done a second & third oil change, it probably would have eventually drained clear(ish) but it's a bit of a waste of new oil. One question? Have you taken off the rocker cover yet, or better still, unbolted the oil pan? What do you see? You will be able to spot proper sludge straightaway. 483k is a lot of miles and you may well have sludge but if the oil's been changed regularly throughout it's life, it could still be good.
 
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Originally Posted by SonofJoe
Originally Posted by RDY4WAR
I have an old truck that I inherited from my grandfather after he passed. It has 483k miles on it, and had been sitting for over 2 years before I got ahold of it. When I drained the old oil out, it was jet black and had the consistency of pancake batter. I put in PYB 10w-30 and let it idle for 15 minutes. Then I drained it and it came out black already. I put PYB back in and haven't messed with it since. I'm not sure if I should add a quart of MMO, let it run another 15 minutes, and dump again... or if there's a better oil for cleaning out such a situation.
First off, don't worry about the oil being jet black. I'm fully aware that it worries folks in the US when it gets that bad but to me, an oil can be jet black and still be fully functional. Diesel oils can happily do HUGE extended drains and spend their entire life black. Second, don't worry about the 'pancake batter' appearance. It doesn't mean the engine has sludged. At a guess, there was a bit of dispersant VII in the old oil. It tends to impart a odd 'gloopiness' quality to the oil which can be a bit disconcerting the first time you see it. Third, be aware that when you do drain an oil, a lot of it can remain held up in the block. I once did an engine test (it might even have been a clean-up test) where I ran a full Ca-based oil, drained it & then added a full Mg-based oil. I was rather surprised afterwards to find so much Ca showing up in the newly added oil and back calculated that 20% of the original oil hadn't drained. I suspect the black 10W30 you drained was black because it intermingled with old undrained oil (not sludge). Had you done a second & third oil change, it probably would have eventually drained clear(ish) but it's a bit of a waste of new oil. One question? Have you taken off the rocker cover yet, or better still, unbolted the oil pan? What do you see? You will be able to spot proper sludge straightaway. 483k is a lot of miles and you may well have sludge but if the oil's been changed regularly throughout it's life, it could still be good.
SonofJoe, thanks for the information. I took a peep under the oil cap with a light and noticed some gunk in there. I cut open the old filter that was on it and it was one of the worst I'd seen, coated in like a black tar. It was a white can purolator. I unfortunately don't know the maintenance history. I moved away after joining the Army. He would mostly just put around his land with the truck, living mostly off the grid, only going to town once or twice a month for necessities. That old truck clocked a lot of hours idling along some muddy trails to his deer stands and crops at 1200 rpm in 2nd gear. Other than a valvetrain tick, the engine idles smooth and revs easy. No blue smoke on startup nor while running. Compression test is low but consistent within 10%. I haven't done a leakdown on it yet.
 
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