Recently did a VOA of a Castrol 5w30 oil spec'd by BMW for use in their diesel engines. VOA done by Polaris labs. I was surprised to see the VOA report showed 10 abs/cm for both oxidation and nitration. How is it possible for oxidation and nitration to show up in an unused motor oil?
Oxidation & Nitration in a VOA report
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Sampling noise perhaps?
Don't both oxidation as well as nitration occur naturally whenever oil is exposed to air, alas, at a slower rate? Even virgin oil is exposed to air at some point, so I would not expect oxidation and nitration figures to be zero. I think most labs just don't test for it in VOA samples.
Originally Posted By: Quattro Pete
Don't both oxidation as well as nitration occur naturally whenever oil is exposed to air, alas, at a slower rate? Even virgin oil is exposed to air at some point, so I would not expect oxidation and nitration figures to be zero. I think most labs just don't test for it in VOA samples.
That is my suspicion also. I think the heat and combustion process of in-use oil just speed it up. Nevertheless, I might add that Polaris considers oxidation/nitration measured at 20 abs/cm as worthy of flagging as "severity level 1" which just confirms my suspicion that the oil analysis labs are very conservative in "flagging" some of these metrics.
Don't both oxidation as well as nitration occur naturally whenever oil is exposed to air, alas, at a slower rate? Even virgin oil is exposed to air at some point, so I would not expect oxidation and nitration figures to be zero. I think most labs just don't test for it in VOA samples.
That is my suspicion also. I think the heat and combustion process of in-use oil just speed it up. Nevertheless, I might add that Polaris considers oxidation/nitration measured at 20 abs/cm as worthy of flagging as "severity level 1" which just confirms my suspicion that the oil analysis labs are very conservative in "flagging" some of these metrics.
Virgin oil will always show some oxidation number. It does not mean the oil is oxidized. Oils with esters will show higher readings.
http://www.polarislabs.com/test-explanations/oxidation.php
http://www.polarislabs.com/test-explanations/oxidation.php
Originally Posted By: Pablo
Virgin oil will always show some oxidation number. It does not mean the oil is oxidized. Oils with esters will show higher readings.
http://www.polarislabs.com/test-explanations/oxidation.php
Interesting. The oil in question is I think a Grp III with some esters I would guess. What about a more ester-rich oil that might then show even higher oxidation/nitration (which really isn't oxidation/nitration - - just a trick of the ASTM test correlating wavelength to oxidation/nitration). Considering the condemnation limits that Polaris uses (30 abs/cm), won't you wind up draining an oil that really isn't all that oxidized/nitrated?
Virgin oil will always show some oxidation number. It does not mean the oil is oxidized. Oils with esters will show higher readings.
http://www.polarislabs.com/test-explanations/oxidation.php
Interesting. The oil in question is I think a Grp III with some esters I would guess. What about a more ester-rich oil that might then show even higher oxidation/nitration (which really isn't oxidation/nitration - - just a trick of the ASTM test correlating wavelength to oxidation/nitration). Considering the condemnation limits that Polaris uses (30 abs/cm), won't you wind up draining an oil that really isn't all that oxidized/nitrated?
That's why you must ALWAYS have a virgin oxidation and nitration number when you do a used oil analysis. It's meaningless without those numbers.
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