ZDDP depletion issue

[friendly_jacek]

I found this nice graph in:
http://www.practicingoilanalysis.com/article_detail.asp?articleid=477

The legend reads: "Figure 5 shows an example of this additive depletion rate. The oil in this example has been used beyond its additive’s useful lifetime. As a result, significant increases in the wear metals were observed during the last few miles of the application."

Looks like 80% depletion in 3000 miles.
Looks scarry. Does anyone know what is the absolute minimum of active (non-hydrolyed) ZDDP to prevent wear?

I'm trying to decide if ZDDP oil additives make any sense if one uses 5000 miles intervals in engines known to be hard on oils (long timing chains and VVT machinery).

If so, should one load the oils up front or in the middle of service?

 

[Zee1]

what happens to the zddp? it can't disappear.

 

[427Z06]

That ZDDP depletion graph is for a particular engine. Your engine may not deplete ZDDP anywheres near as fast. If you have a modern engine with rollerized valvetrain components, you can almost count on it.

Further, other additives are now starting to replace some of the functionality of ZDDP.

 

[sxg6]

quote:

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Originally posted by friendly_jacek:
As a result, significant increases in the wear metals were observed during the last few miles of the application

---

This goes against the info i've seen on this site and in uoa's. From what i've read and seen it seems that most wear occurs early on in an oci, and not towards the end.

 

[friendly_jacek]

quote:

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Originally posted by Zee1:
what happens to the zddp? it can't disappear.

---

It breaks down to pieces and the break down is escalated by temperature and especially water (hydrolysis).
The P and Zn elements stay in the solution as identified by traditional UOA but with no or limited functionality.

I have to admit this is new stuff to me but very interesting.

 

[Shannow]

Thanks,
that's been one of the questions I've been struggling with for ever.

 

[boxcartommie22]

thats funny i guess iam not silly at all ...i learned when i was i teen to change my oil and filter every 1500 miles

 

[JohnnyG]

Looks like total ** to me. What is "Absorbance Area" anyway? No particulars are given. Not the engine type, oil type, driving conditions, ambient temperature, egine temp, rpms, milage, condition of the engine, NOTHING. If you read here you will soon find out that changing your oil every 1500 miles is a TERRIBLE waste of natural resources, and a HUGE waste of money. Are you sure you don't own stock in an oil company?

 

[TooSlick]

ZDDP depletion can also be caused by it's role in minimizing oxidation. In fact I'd say that may be a more direct contributor to the remaining functionality of the additive.

TS

 

[dwendt44]

In the 50's, 1500 miles was probably a good OCI.

 

[Pablo]

If you have an oil that depletes as the graph shows, it's time for a new oil.

 

[surfstar]

quote:

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Originally posted by Pablo:
If you have an oil that depletes as the graph shows, it's time for a new oil.

---

BINGO!

That graph shows after 3k miles, that only ~20% of ZDDP remains! Doesn't seem to pan out with the tons of UOAs we have on here.

 

[Winston]

quote:

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Originally posted by sxg6:
...From what i've read and seen it seems that most wear occurs early on in an oci, and not towards the end.

[/QB]

---

We have seen that wear metals spike up initially. However, I don't know that conclusively means that wear spikes initially.

 

[Ray H]

One of the dangers of selectively presenting ONE aspect of a study is coming to an unsupported overall conclusion. The following, quoted from the original source, may present a bit more balance to this discussion:

quote:

---

Figure 6 illustrates how ZDDP depletes reasonably early in this application; however, there are still several intermediate components that are formed which last well into the oil’s lifecycle. Some of the thermal and oxidative decomposition by-products still exhibit the antiwear or antioxidant properties of the original additive. The final decomposition product, phosphate, starts to appear in this used oil about one-third into the lifecycle. It was shown to grow to a steady state concentration through the remainder of the oil’s life.

---

Perhaps it's reasonable to think of ZDDP as a "time release" distributor of phosphate and other secondary EP protective chemistries.

[ August 02, 2006, 10:57 AM: Message edited by: Ray H ]

 

[nortones2]

Maybe it takes 2000 miles to activate: its out of solution but chemically adsorbed in place in the hot spots. http://www.nsls.bnl.gov/newsroom/publications/activityreport/1998/RU1139.PDF

 

[JohnBrowning]

A lot of European and Asain cars still do not use rollerized valvetrains. So ZDDP depletion could be a possability if the OCI is over extended or if the ZDDP levels continue to drop!

 

[Schmoe]

Wonder what exactly is high temperature and high levels of moisture that is fitted into the graphics to show such high depeletion rates? Nuclear reactors on submarines????

 

[GMorg]

It is not important for this discussion, but the following helps explain the units used for this type of data.

A reciprocal wavelength (cm-1) is a simple convenient unit for comparing energies when dealing with spectra.

An actual energy can be obtained by multiplying cm-1 by hc (Planck's constant times the speed of light). To convert from cm-1 to kJ/mol one uses
Planck constant
h = 6.62606876 x 10-37 kJ s
Speed of light
c = 2.99792458 x 1010 cm s-1
Avogadro constant
NA = 6.02214199 x 1023 mol-1

or 1.196266 x 10-2 kJ mol-1 cm.

 

[427Z06]

Whoa Nelly! I walked away for a while and you guys are quickly into Planck's constant and Avogadro's number. I suspect Ray H had something to do with this.

 

[TomJones76]

I seem to remember that someone (Molakule?) posted the lowest effective concentration of ZDDP one time, and it turned out that it was some ridiculously low number... somewhere between 200 and 600 PPM.