Typically we see UOA vs VOA showing additives such as zinc and phosphorus dropping over the OCI. So why not take an additive like GM EOS or SLOB that has high levels of zddp and add them incrementally, a few ounces at a time, say every 1000 miles or so throughout the OCI? The idea would be to maintain a relatively constant level of zddp over the OCI. Adding regular oil for top up would not have the same effect, since the fresh oil would only have its additives lowered through dilution with the existing, partly additive depleted oil in the crankcase.
Additive depletion over OCI
- Thread starter TallPaul
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Patman
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What would honestly be the purpose of this though? Even with this additive depletion, the UOAs in those cases still often show low engine wear and strong TBN at the end.
I guess I'm the type of person that does not want to have to do anything in between oil changes though, no adding of any chemicals, no oil filter changes, no adding of makeup oil, nothing.
I guess I'm the type of person that does not want to have to do anything in between oil changes though, no adding of any chemicals, no oil filter changes, no adding of makeup oil, nothing.
Paul, what kind of car? If it's a big honkin V8 with lots of lift, fancy cams, all that, you're going to run an HDEO anyway.
Now if you're talking a vehicle with a bypass system, running the oil 25K or longer, there's a case to be made, but lots of the TBNs I've read for standard PCMO don't show a meanful TBN drop through 8 and 10K. Which of course, is he refrain against these 3K OCI lots of folks are still committing. Especially with newer cars, fuel injection, rollerized cams, etc.
Now if you're talking a vehicle with a bypass system, running the oil 25K or longer, there's a case to be made, but lots of the TBNs I've read for standard PCMO don't show a meanful TBN drop through 8 and 10K. Which of course, is he refrain against these 3K OCI lots of folks are still committing. Especially with newer cars, fuel injection, rollerized cams, etc.
I'm starting to feel that way too Pat. I've spent the past year tinkering with LC and ARX additions, ARX cleanings and rinses, 6 UOAs, and I've got to the point where I think I know what's going on with oil and with my engine, and I'm losing interest in all this playing around. I guess that's where all the learning and experimenting was headed anyway now that I think about it. But for the first time since I came here a little over a year ago, I'm looking forward to just changing oil and letting it run for the OCI that I now know is good for my engine. Perhaps periodic UOA to check to see if that #@$%! internal water pump is starting to leak.
Patman
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I don't even like checking my oil anymore!
In a by-pass system, say, long-haul trucks, they run long, LONG oci, yes? Surely there, additive depletes, yes? If so, how do they accomodate that?
14 gallon sumps?
Quote:
I don't even like checking my oil anymore!
Blasphemer!!! "Give us Barabbas!!!"
You're kidding! 14 GALLONS?
Holy Moly! I had no idea. Makes sense, I suppose. The long haulers are huge.
TallPaul, I think you need to read some of the research that clearly demonstrates that overzealous amounts of ZDDP may do more harm than good in many applications.
No we don't. There may be a small initial drop while volatile components make their way to the exhaust stream, but we don't see any significant drop during the rest of the OCI. Now if your talking degradation of the compounds, that's a different story and can't be directly measured with a $20 UOA.
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Yeah ..even though we accept that zddp decays on a sacrificial per rpm basis ..we still see zinc levels in the UOA that don't show any linear decay.
Ok, so here's a UOA posted by Titan awhile back:
First column is this UOA, second is Universal average of those UOA's with only 4600 miles.
Al 3/3
Chr 0/1
Iron 7/7
Cu 3/5
Pb 2/6
tin 1/0
Moly 46/72
Nickel 0/0
Manganese 0/0
Silver 0/0
titanium 0/0
K 0/1
Boron 1/46
Silicon 21/11
Na 2/7
Ca++ 2122/2195
Mg 9/108
Phos 605/703
Zn 727/831
Barium 0/1
Viscosity 58.4
Flash 380
insoluable 0.2
Where's the zinc, moly and boron going, and why doesn't the calcium show the same rate of reduction across the longer drain? Are these all exhaust losses, or does the UOA not show sheared/depleted/altered, but still present, additive?
Most additives like Zn/P/Ca/Mg, still show up in UOA's at more or less their baseline levels - even after they have been rendered inactive in performing their function. The exceptions are MoDTC (moly) and boron, which start to deplete from the day the oil is poured into the engine.
An experienced analyst can actually track the level of Boron and determine when the oil has reached the end of it's useful life. The borate esters combine synergistically with ZDDP to form low friction, AW films, so when the boron is depleted the ability of the oil to minimize wear is degraded.
An experienced analyst can actually track the level of Boron and determine when the oil has reached the end of it's useful life. The borate esters combine synergistically with ZDDP to form low friction, AW films, so when the boron is depleted the ability of the oil to minimize wear is degraded.
Ok, so here's a UOA posted by Titan awhile back:
First column is this UOA, second is Universal average of those UOA's with only 4600 miles.
Al 3/3
Chr 0/1
Iron 7/7
Cu 3/5
Pb 2/6
tin 1/0
Moly 46/72
Nickel 0/0
Manganese 0/0
Silver 0/0
titanium 0/0
K 0/1
Boron 1/46
Silicon 21/11
Na 2/7
Ca++ 2122/2195
Mg 9/108
Phos 605/703
Zn 727/831
Barium 0/1
Viscosity 58.4
Flash 380
insoluable 0.2
Where's the zinc, moly and boron going, and why doesn't the calcium show the same rate of reduction across the longer drain? Are these all exhaust losses, or does the UOA not show sheared/depleted/altered, but still present, additive?
This is on a 2.5 Subaru Legacy, '07, 8000 miles on oil, PP 5-30, in case that makes any difference on some of those levels.
First column is this UOA, second is Universal average of those UOA's with only 4600 miles.
Al 3/3
Chr 0/1
Iron 7/7
Cu 3/5
Pb 2/6
tin 1/0
Moly 46/72
Nickel 0/0
Manganese 0/0
Silver 0/0
titanium 0/0
K 0/1
Boron 1/46
Silicon 21/11
Na 2/7
Ca++ 2122/2195
Mg 9/108
Phos 605/703
Zn 727/831
Barium 0/1
Viscosity 58.4
Flash 380
insoluable 0.2
Where's the zinc, moly and boron going, and why doesn't the calcium show the same rate of reduction across the longer drain? Are these all exhaust losses, or does the UOA not show sheared/depleted/altered, but still present, additive?
This is on a 2.5 Subaru Legacy, '07, 8000 miles on oil, PP 5-30, in case that makes any difference on some of those levels.
I have often wondered this as well. It was my understanding that the GM OLM algorythm was modelled around ZDDP depletion, which depletion was viewed to be the key indicator of the need for an oil change.
Assuming TBN is ok, the oil is still in grade and there's an acceptable level of insolubles, I would have thought that doping the oil with an additional amout of "active" ZDDP late in the OCI might assist in extending that OCI a little longer.
I'm sure there are other factors that I'm missing, so I'm interested in hearing about the other considerations.
Assuming TBN is ok, the oil is still in grade and there's an acceptable level of insolubles, I would have thought that doping the oil with an additional amout of "active" ZDDP late in the OCI might assist in extending that OCI a little longer.
I'm sure there are other factors that I'm missing, so I'm interested in hearing about the other considerations.
Can't compare to Universal Averages. Must compare to same oil but at different mileages, preferably during same oil use interval. Doesn't matter anyway. Zinc in UOA doesn't go down significantly; the atoms don't disapear but the ZDDP molecules break down into other atoms and molecules during both wear reduction function and antioxidant function. This 1988 study measured ZDDP depletion (NOT zinc or phosphorous atoms). 45-50% depleted after 570 hours of use.
http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5920032
I think a LITTLE periodic dosing of GM EOS during long oil changes with some oils (generally SM oils, NOT HDEOs or similar oils) is a good idea. The anti-oxidant effect may be more beneficial than the anti-wear effect in semi-exhausted oil. I wouldn't do it to the point of giving the oil HDEO levels of ZDDP by the time you change the oil though. Ending up with 1000 PPM of zinc should be fine.
http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5920032
I think a LITTLE periodic dosing of GM EOS during long oil changes with some oils (generally SM oils, NOT HDEOs or similar oils) is a good idea. The anti-oxidant effect may be more beneficial than the anti-wear effect in semi-exhausted oil. I wouldn't do it to the point of giving the oil HDEO levels of ZDDP by the time you change the oil though. Ending up with 1000 PPM of zinc should be fine.
How about posting the VOA figures next to those? Wouldn't that be more interesting to compare as far as this discussion goes?
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