geeaea said:
Most of your analytical machinery read up to 5um particles.
Perhaps you may be aware of DalessII, who did a filter test on JU. He was some banging researcher and got some lab to run tests for him free. His numbers were through the roof as far as wear metals. That lab "digested" the samples with acid and reduced everything (large particles small particles) to the true particle size for the test.
Most UOA labs can't/don't do that (none that I know of). The spectrography reads particles of 5um or lower. A "normal" UOA under digested criteria would have wear metals in the thousands in terms of ppm and would be totally variable based on the level of filtration. If you've ever seen particle counts on oil samples, you can see how a PureOne is going to give you a lower particle count than the standard lowball Fram. If you have bypass filtration, then you attenuate the larger particles even more. A sample drawn from such an engine, being digested, would show substantially less ppm (although still very high by UOA standards).
We used AA in my former job as an industrial waste treatment specialist. We would test for various elements. If we wanted "free" copper ..it was a straight sample. If we wanted "total" copper, it was digested. Throw a penny in my effluent going to the river.....no problem for the DEP/EPA. Digest that penny and I was committing a major environmental violation.
..but beyond all this, the oil blenders are taking care of those who still have flat tappet cams ..as much of a vanishing breed as we are. Right now I'm testing SM 5w-20 Pennzoil Platinum in my wife's 4.0. Now I've got a high volume aftermarket oil pump and have Mopar roller rockers ..but my lifters are still OEM as is the cam. My wear indicators are not out of line with my 2.5 4 banger using Rottella T synth 5w-40 which is an SL. Our spring rates are 200lbf (force) max ...not 200 lbs on the valve seats. Those playing hotrod with their SBC's out of the Jeg's catalog have to worry about breaking in and maintaining their aggressive cams.
Keep in mind that many of the advances in contemporary oils is in terms of deposit control. A well cared for engine, even to OEM recommendations, typically will have very low levels of deposits. Oils now have tremendous ability to keep stuff in suspension. Advances in base stock technology have radically reduced the need for viscosity index improvers that used to shear routinely in service. The reason that you see so many manufacturers going to 20 weight oils is because most of their engines were already running on them after 1500 miles or so due to polymer shearing. The trick was bringing a 5w-20 oil to market. Ford took care of that by seeking CAFE certification using them.
In the past, favorable Fe levels were only attainable with higher visc oils in this engine. Over the past few years many 30 weights have been shown to contain this inherent characteristic. This points to modern additive combinations being able to trump visc in many instances. I'd say that fuel dilution, due to injector imbalance, is more responsible for higher Fe levels in this engine than is due to the oil's anti-wear properties.
The I am totally puzzled at this point. Just what equipment are they using then for metal analysis. How can they tell what metals and what percent of metal is in an individual particle if they don't digest the sample? XRF can be used to get the alloy analysis of a solid metal surface, and I have heard of it being used in soil analysis for trace metals in soil, but I am not sure how accurate the values are that it generates. It may explain how they produce so many test results for few dollars (that has always concerned me).
Personally I would want the whole story, but that would probably be too costly. Not familiar with "DalessII,", but it sounds imteresting, also makes my point about the bulk of the wear metals (mass wise) being in the filter and the sediment in the bottom of the oil pan, in places where there is little circulation.
From what you are saying, I must question what they are reporting as metals, if it is not total metals in the used oil, then what is it, and how are they are measuring it? What is it not reporting?????
Free copper samples should be filtered first to assure a more homogeneous sample is introduced into the AA, if they use AA, which they do for EPA waste water tests, other wise you are likely to not get repeatable results in the test if there are any TSS solids in the sample. Just one particle of copper in the tested sample pulled from the bulk sample would skew the test results, if they used AA.
If they used the ancient wet methods it would be OK as it would only show ionized metals (Free Cu in ionized metal salts) but the old wet methods are subject to multiple interferences from other ionized metals, and is also subject to interferences from strong chelating agents.
We are in agreement on the effect of different quality filters on the total metal left in the oil, but that just makes my earlier point that a UOA test is not the be all test for engine wear! One would need to wash the engine, & filter, collect, weigh and analyse the washings, open the used filter, wash, collect and weigh the filtered mass from the filter and analyze it as well, then add in the total metals from the oil, add all three and look at the total mass of metal lost from engine wear and corrosion to get the total, real picture. And to make matters worse, one would need to start with a clean engine before each mileage..oil test began.
Regarding "Right now I'm testing SM 5w-20 Pennzoil Platinum in my wife's 4.0."
All I can say is you are brave soul using Penzoil, and using 5W20 SM on top of it. Penzoil ate the only engine I ever wore out.
Regarding "My wear indicators are not out of line with my 2.5 4 banger using Rottella T synth 5w-40 which is an SL."
Based on what you are saying about how the UOA test is actually done, and what it is reporting, and even worse what it is not reporting, I am at the point where I would seriously question whether a UOA is even going to register a serious metal wear problem in either engine.
In fact it is begining to sound like the only way a really bad UOA analysis would happen is if the oil viscosity increased substantially reducing the settling rate of metal particles to the bottom of the oil pan, and if the acid neutralizers had been depleted alowing more of that metal to be disolved into the oil.
I have had my suspisions that the polymers were shearing based on the hot, long highway drive engine oil pressure drops everyone has been reported.
I use to run straight 30WT (wnter) and 40WT (summer) Exxon, and never saw more than a 5 lb presure drop from cold to fully heated up operation.
I only recently (like 7 years ago) starting using multiviscosity oils myself.
I suspect the switch to 5W20 WT oils is also driven by fuel mileage needs combined with tighter engine tolerances that newer production machinery has made possible in the newer engines, and they cannot run 20W50 oils with those tight tolerances. The older engines like mine do not have the tighter clearances that the newer engines have and they can run much higher viscosity oils, and in fact run better on higher viscosity oils.
If I had a brand new 4.0, I would probably run 10W30 Mobil 1 EP synthetic in it. If I lived in Canada and it was new engine I might go with the 5W20 synthetic.
The topic is sort of old, but the newest API spec oils are just taking over the shelves now, with even less ZDDP that the last change did several years back, including reduced ZDDP in the Rotella T for diesels due the new 2007 diesels having cat converters and exhaust particluate filters. :rattle:ULSD fuel is involved in the conspiracy 
