Skewing of UOA by Cleanup of Wear Metals

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I've noted through several threads recently a number of disagreements about whether or not UOA results may be skewed when new oil cleans up wear metal containing deposits in the engine. I suppose this might happen either because the new oil is not exhausted like the old, or because it's just better at cleaning. Noting the disagreement on this issue, I decided to post this blurb I found while reading a Royal Purple PDS.

Originally Posted By: From the RP PDS
Note: Engine oil’s solvency cleans wear metals and deposits left by previous oils. These wear metals and deposits can cause abnormally high values on used oil analysis until the engine is clean.


For those who'd like to go direct to the source, click here.

I do not profess to know whether or not this is correct. Offered simply for consideration and comment as desired.
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+1

Not sure f the high Fe M1 UOAs are truly consistent with such a sampling regimen. Ive never had high Fe, but we routinely long-term use it...
 
Makes sense to me, as I always noticed that the wear metals were lower on the second UOA after I switched a car over to GC compared to it's first UOA.
 
We've seen it many times with Red Line. It's not ALWAYS going to happen ..but when it does ..it's almost like run in shedding.
 
Thanks. I remember reading about this a few years ago. I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc.. People should at least run a few UOA's when switching from brand to brand before jumping to conclusions.
 
Originally Posted By: buster
Thanks. I remember reading about this a few years ago. I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc.. People should at least run a few UOA's when switching from brand to brand before jumping to conclusions.


I agree. I posted this quote because there had been some very sharp-edged, even sarcastic, condemnation of this idea in recent months here on BITOG. It's interesting that some were jumping to the conclusion that this was a non-phenomenon, when one oil maker (RP) has it on their website, and the reps from another (RL) will discuss this with you if you ask.
 
Originally Posted By: buster
I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc..


Mobil 1 has high polar base oils? Am I missing something here?

PAO has the lowest polarity of all the base oils, and group III isn't much better? I believe M1's group V (AN's, esters?) content is less than 10%, based on the Korean MSDSs.

What am I missing?
 
Is it possible a good filter can skew results too? The wear is still going on at the same rate however it doesn't show as much in the sampled oil because the filter is trapping it? If so then the test sample won't mean much, my guess is if you want real accuracy have the filter checked by a lab as well.
 
Originally Posted By: Ben99GT
Originally Posted By: buster
I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc..


Mobil 1 has high polar base oils? Am I missing something here?

PAO has the lowest polarity of all the base oils, and group III isn't much better? I believe M1's group V (AN's, esters?) content is less than 10%, based on the Korean MSDSs.

What am I missing?


Yes, Mobil 1 does have polar base oils including POE and AN's. Both are very polar.
 
Originally Posted By: buster
Originally Posted By: Ben99GT
Originally Posted By: buster
I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc..


Mobil 1 has high polar base oils? Am I missing something here?

PAO has the lowest polarity of all the base oils, and group III isn't much better? I believe M1's group V (AN's, esters?) content is less than 10%, based on the Korean MSDSs.

What am I missing?


Yes, Mobil 1 does have polar base oils including POE and AN's. Both are very polar.


And I doubt it would take a tremendous amount of these in the blend to pick up stuff that's easily cleaned.
 
Originally Posted By: buster
Originally Posted By: Ben99GT
Originally Posted By: buster
I think this occurs in synthetics that have high polar base oils like Redline, Mobil 1 etc..


Mobil 1 has high polar base oils? Am I missing something here?

PAO has the lowest polarity of all the base oils, and group III isn't much better? I believe M1's group V (AN's, esters?) content is less than 10%, based on the Korean MSDSs.

What am I missing?


Yes, Mobil 1 does have polar base oils including POE and AN's. Both are very polar.


Why isn't redline showing consistently higher iron trends? Surely it's a far more polar oil than mobil1 and should be, according to the 'iron is soluble in oil' theory, cleaning much more mystery iron than mobil1 with it's ~15% max polar fluid blend.
 
Ummmm, we've been discussing cruddy first-run RL UOAs since I joined here, five years ago. I just found one from back in 2002, after about 15 seconds of looking.

EDIT: And if the phenomenon is not for real, why would RP, an entity we hope knows something about synthetic oil, describe it on their website???
 
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Originally Posted By: buster
Yes, Mobil 1 does have polar base oils including POE and AN's. Both are very polar.


Yea, but M1's AN and/or (maybe) POE content is very low. A good 80-90% of M1 is GroupIII and PAO. Nothing wrong with that, I just doubt M1 is a particularly polar motor oil.
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