Curious as to the depleted ZDDP levels after normal mileage from oil analysis results. What numbers have you seen? In other words, are you seeing drastic depletion or minimal?
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So, the consensus is that more ZDDP content in oil does not equate to more protection...only takes longer to deplete?
ZDDP is sacrificial, zinc isn't. The instrumentation used for UOAs only sees zinc. It can't differentiate whether the zinc is from ZDDP or ZnCl. The compounds in the sample are broken down into their individual atoms in the plasma. The instrument is tuned to see the wavelength of light emitted by Zn when an electron is kicked up an energy level by the heat of the plasma. The original source of the zinc can't be determined.You don't see ZDDP depletion in UOAs. There's no concrete reason why it doesn't deplete considering it is a sacrificial additive. Speaking with a retired chemist who made ZDDP for decades, he didn't know why either. It's one of those mysteries of lubricants that's yet to be solved. There are a few theories. My own personal theory is that elements of zinc, phosphorus, and sulfur get kicked back in circulation as old anti-wear tribofilms are replaced or replenished, and also from attachment to other particles in the oil.
ZDDP is sacrificial, zinc isn't. The instrumentation used for UOAs only sees zinc. It can't differentiate whether the zinc is from ZDDP or ZnCl. The compounds in the sample are broken down into their individual atoms in the plasma. The instrument is tuned to see the wavelength of light emitted by Zn when an electron is kicked up an energy level by the heat of the plasma. The original source of the zinc can't be determined.
You are essentially correct on why the values don't change much. The tribofilm is in a constant state of flux being formed and "used up" at the same time. Each time the tribofilm is called into action the ZDDP molecule is broken down into smaller and smaller pieces until they are no longer functional anti-wear compounds. The ratio of functional to non-functional Zn compounds changes as the oil ages. If the oil is run too long there are not enough functional compounds to form an effective tribofilm. The concentration of Zn in the oil remains about the same, with any difference due to dilution/concentration of the oil or analytical error.
Ed
So, short story is that there is nothing concrete to substantiate claims that more ppm of ZDDP is providing greater protection?
Link to those "tons" if generally available. I'm speaking of average Joe's ability to cypher which oil he genuinely needs for a given application.
Boundary Friction of ZDDP Tribofilms
Film Thickness and Friction of ZDDP Tribofilms
The Mechanism of ZDDP Antiwear Film Formation
The History and Mechanisms of ZDDP
There's just a few of many. Hugh Spikes is credited in many of the white papers involving ZDDP. He's a master of his craft and legend among tribologists. Anything he states, you can take to the bank.
You do have the wear protection that's guaranteed by many manufacturer approvals. Most of the European ones have stringent wear requirements.Interesting reads, but none of these really answer the question of what is actually required for our engines. The average consumer still has no reliable information other than someone's statement such as "I've never had a failure using brand X"...not really compelling or helpful.
I believe the link I provided shed more light on the properties, formations and behavior of ZDDP than any I have seen to date. The question of just how much ZDDP is required remains unanswered and unavailable to the average Joe. I would have liked to see some similar tests carried out with consumer available oils, but I understand this is a costly and time consuming process.
You do have the wear protection that's guaranteed by many manufacturer approvals. Most of the European ones have stringent wear requirements.
Uhh, approvals and the tests in SAE J300 are real world. What would you suggest instead?Sorry, but I have no knowledge of any oil manufacturer replacing a toasted engine. I would prefer some real world testing over a symbol or label on a bottle.
Those are nothing more than tests for specific properties just as described in the above links...exercises in science if you will. That does nothing to describe the outcome of a specific oil for you or I. According to the general consensus My Stock Eliminator engine should be in shambles from it's paltry oil ZDDP content.Uhh, approvals and the tests in SAE J300 are real world. What would you suggest instead?