Primary vs Secondary ZDDP

[RDY4WAR]

Originally Posted by SonofJoe
Originally Posted by RDY4WAR
I've never been able to simply accept something for what it is. I have to know why or how. I'm also stuck at home for several weeks healing a broken back so I have A LOT of time on my hands.


Sorry to hear about your back. Hope the recovery goes well.

Regarding your comment about 'needing to know how & why', I suspect you would make a first rate lubricant researcher but a terrible oil formulator!

I used to know one of the guys mentioned in the R&D papers cited above & we worked together on stuff from time to time. He was a really nice guy, extremely personable, highly cooperative & far more intelligent than me. The quality of his work was always top notch & he's published a lot of industry papers.

That said, I would have to say that in all the time I knew him, his impact on COMMERCIAL oil development was virtually zero (as in zip, nada, nichts, rien!).

The people that control commercial oil development are generally known as 'formulators'. These are the people that design oils to pass the big engine test programs that allow an oil to be labelled up as SN/A3/B4/MB this/VW that/BMW the other. The skill set you need to do this successfully is truly vast! You have to be part-chemist, part-chemical engineer, part-mechanical engineer, part -statistician, part-salesman plus being a pretty slick cost-accountant. Focussing on one specific aspect of oil design (eg ZDDP/Ashless interaction) is a luxury you can ill afford because you have to simultaneously juggle hundreds of variables in your head, anyone of which can individually cause a program to come to a juddering, embarrassing & expensive halt! To be a good oil formulator, you need to be comfortable with 'ambiguity' and accept that there will never be enough time or money to understand what you're doing!

Hope that helps...


I'm definitely not an ambiguous person. I like exact answers, exact routines and patterns. My wife swear's I have aspergers.

I'm interested in the coefficient of friction. Ideally, you'd want that as low as possible while also having great wear protection. I wonder if additives like Mo, Sb, and B could provide the lower friction while allowing for a shorter chained, secondary ZDDP to provide the best wear protection. Then this gets expensive. I also wonder at what point the coefficient of friction gets too low say to the point that roller lifters stop rolling and instead glide/slide over the cam lobes.

Thanks for all of the information thus far. It makes me want to dig deeper.

 

[Gokhan]

Explanation of an interesting study that was recently published in Science. They finally figured out how ZDDP films are formed using an atomic force microscope (AFM). It turns out that the film is initially caused by the high pressure generated by the contact forces, as these contact forces cause ZDDP to react with the surface. As ZDDP film thickens, it becomes less and less stiff, acting more like a cushion layer. This causes the contact pressure to drop, which slows down and terminates the chemical reaction and the film self-terminates growing. It's beautiful the way it works.

Researchers address long-standing mysteries behind anti-wear motor oil additive
March 13, 2015 by Evan Lerner, University of Pennsylvania
https://phys.org/news/2015-03-long-standing-mysteries-anti-wear-motor-oil.html

 

[Gokhan]

A couple of very interesting studies on the synergistic effect of ZDDP and moly.

First, it appears that there is still no substitute for ZDDP as an antiwear additive. Without ZDDP, the wear would be really bad. Moly or other additives alone don't seem to work.

Second, while ZDDP is very good in reducing wear, moly greatly increases its effectiveness, making it even better. In addition, ZDDP also increases friction but moly decreases friction, making up for this negative effect and further decreasing the coefficient friction to as little as 0.05 or smaller.

It looks like motor oils use a combination of primary ZDDP and secondary ZDDP, however, with more secondary than primary in the mix. As I explained earlier in this thread, short-chain secondary ZDDP with neutral (as opposed to basic) ZDDP molecules is the best in reducing the wear. However, since it's also the least stable form of ZDDP, they use some primary in the mix as well.

Now, a four-ball wear test. Notice how ZDDP makes a difference and how moly increases its effectiveness. Note in the figure the abrupt transition to high wear. Moly delays this transition:

Then, a comparative study of different blends:

Moly I is dinuclear moly. Moly II and III are low-sulfur moly. Note the ppm's for S, P, Zn, and Mo in the table on the right:

Here are the results. 600 ppm dinuclear moly with ZDDP (Blend 5) did best both in friction and wear. Note that it has the highest sulfur with 2,000 ppm (0.2%), which is at the ACEA C1 and C4 limit and close to the C2, C3, and C5 limit (0.3%).

They didn't study the trinuclear moly, which Infineum claims to work at as little as 50 - 100 ppm (more a claim than fact probably), but they are Oronite; so, they compete with Infineum.

Below is a good presentation by Paul Wilson of Infineum UK on motor oil and additives, talking about antiwear, extreme pressure, and friction modifier additives among many others. Note that a common organic friction modifier is oleic acid -- a type of vegetable oil (abundant in peanut oil, 61% of canola oil, up to 85% of sunflower oil, etc.).

https://warwick.ac.uk/research/priorities/materials/publications/wilson_presentation_to_warwick.pdf

References:

The mechanism of lubrication by molybdenum disulphide dispersed in oil and the effect of a zinc dialkyldithiophosphate additive
J. M. Thorp
Auckland industrial Development Division, D.S.I.R., P.O. Box 2225, Auckland (New Zealand)
Received: August 4, 1972 (Yes, an old but good one)
https://www.sciencedirect.com/science/article/pii/0043164873900410

Friction Reduction and Antiwear Capacity of Engine Oil Blends Containing Zinc Dialkyl Dithiophosphate and Molybdenum Complex Additives
K. KOMVOPOULOS (Fellow STLE) and S. A. PERNAMA
University of California, Department of Mechanical Engineering, Berkeley, California 94720
E. S. YAMAGUCHI, Chevron Oronite Co., Richmond, California 94802
P. R. RYASON, Tamalpais Tribology, Fairfax, California 94930
Published online: February 24, 2007
https://www.tandfonline.com/doi/abs/10.1080/05698190500544353

 

[SonofJoe]

Originally Posted by RDY4WAR
Originally Posted by SonofJoe
Originally Posted by RDY4WAR
I've never been able to simply accept something for what it is. I have to know why or how. I'm also stuck at home for several weeks healing a broken back so I have A LOT of time on my hands.


Sorry to hear about your back. Hope the recovery goes well.

Regarding your comment about 'needing to know how & why', I suspect you would make a first rate lubricant researcher but a terrible oil formulator!

I used to know one of the guys mentioned in the R&D papers cited above & we worked together on stuff from time to time. He was a really nice guy, extremely personable, highly cooperative & far more intelligent than me. The quality of his work was always top notch & he's published a lot of industry papers.

That said, I would have to say that in all the time I knew him, his impact on COMMERCIAL oil development was virtually zero (as in zip, nada, nichts, rien!).

The people that control commercial oil development are generally known as 'formulators'. These are the people that design oils to pass the big engine test programs that allow an oil to be labelled up as SN/A3/B4/MB this/VW that/BMW the other. The skill set you need to do this successfully is truly vast! You have to be part-chemist, part-chemical engineer, part-mechanical engineer, part -statistician, part-salesman plus being a pretty slick cost-accountant. Focussing on one specific aspect of oil design (eg ZDDP/Ashless interaction) is a luxury you can ill afford because you have to simultaneously juggle hundreds of variables in your head, anyone of which can individually cause a program to come to a juddering, embarrassing & expensive halt! To be a good oil formulator, you need to be comfortable with 'ambiguity' and accept that there will never be enough time or money to understand what you're doing!

Hope that helps...


I'm definitely not an ambiguous person. I like exact answers, exact routines and patterns. My wife swear's I have aspergers.

I'm interested in the coefficient of friction. Ideally, you'd want that as low as possible while also having great wear protection. I wonder if additives like Mo, Sb, and B could provide the lower friction while allowing for a shorter chained, secondary ZDDP to provide the best wear protection. Then this gets expensive. I also wonder at what point the coefficient of friction gets too low say to the point that roller lifters stop rolling and instead glide/slide over the cam lobes.

Thanks for all of the information thus far. It makes me want to dig deeper.



I got into the Lubes business in '97 after a couple of decades of being in Fuels. It was a very difficult transition, not least because no one I asked questions to seemed to have the first clue as to what they were doing!

So I set about trying to find my own answers; how oils blend, what additives actually do (as opposed to what they're 'supposed' to do), what affects what, etc, etc. It was quite a steep learning curve.

In that time I had a brief flirtation with Coefficients of Friction (while working with my aforementioned colleague on fuel economy). It's so long ago, I can't recall the work in detail but I do remember working the numbers quite hard. I ultimately came to the interesting, if somewhat heretical, conclusion that yes, while 'stuff' can lower the Coefficient of Friction, in the context of commercial oil development, the concept was completely meaningless. It just seemed to me that lowering CoF, didn't actually DO anything! It didn't materially reduce wear or improve fuel economy in the same way that other stuff (eg bulk viscometrics) measurably did. After that, I never bothered with it ever again.

That probably won't help you but I just wanted to highlight that there's a vast chasm of difference between the world of lubes/tribology R&D and the entirely separate process of defining a oil which goes on a shelf to be sold. In the world of engine oils, Google isn't necessarily your friend.

 

[RDY4WAR]

SonofJoe

That does help tremendously. I like these kinds of discussions.

Going back to an earlier point, being a formulator, what is your take on running a diesel oil in a gas engine for the ZDDP? Is there anything in the formula of diesel oils that would make not safe, or at least not optimum, for a gas engine?

 

[SonofJoe]

Originally Posted by RDY4WAR
SonofJoe

That does help tremendously. I like these kinds of discussions.

Going back to an earlier point, being a formulator, what is your take on running a diesel oil in a gas engine for the ZDDP? Is there anything in the formula of diesel oils that would make not safe, or at least not optimum, for a gas engine?


Virtually all the oils I ever developed were dual-use oils, formulated for both gasoline & diesel engines. Even the lowly SG/CD oils I did got a look-see at a diesel engine!

There are a few differences between PCMOs & HDDOs. More ZDDP is one. Because HDDOs have to deal with soot, they tend to contain more ashless dispersant and/or dispersant VII. HDDOs generally contain less antioxidant & usually no Friction Modifier. Finally, HDDOs tend to be available in a narrower range of heavier viscosity grades so you lose much of the fuel economy performance of the oil.

None of these things should put you off using an HDDO is a gasoline engine. I would add however that HDDOs do tend to be more expensive so it's a bit of a waste.

 

[RDY4WAR]

Thanks. That pretty much confirms what I already knew.

Another question for you. If there was an additive in engine oil that you favored more than any other, what was it and why?

Also going back, what do you mean by bulk viscometrics?

 

[SonofJoe]

My personal favourite additive? Easy...ZDDP (light mixed primary/secondary)! Developed in WWII & still by far & away the most ubiquitous, multifunctional, cost-effective engine oil additive ever invented.

However the answer does depend on what 'philosophically' you're formulating for. Are you formulating to pass a engine test program or for 'real-life usage' (these are deffo not the same thing). Are you formulating for lowest cost, best cost-effectiveness, novelty features or out and out bragging rights? Are you formulating to satisfy The Usual Customer (ie The OEMs) or the actual customer (ie Joe Public). All these factors have a profound impact on what sort of oil you end up with.

For what it's worth, I sit (possibly alone!) in the camp of highly cost-effective engine oils for everyday 'real-life' use, with DI & VII minimised and the benefits of base oil maximised. My ideal oil would be a 10W20, Group II/III mix with 1000ppm Phos, 8 TBN (from Magnesium Sulphonate), a smidge of Moly, a splash of heavy Group I and as little ashless as I could reasonably get away with. I would look for a sub-10% Noack Volatility to minimise the risk of late onset Oil Control Ring Stick & a concomitant rise in oil consumption. The oil would be guaranteed API/ILSAC stupid spec-free and contain no elements from the Periodic Table with 'sexy' names but zero utility.

 

[Shannow]

I'd buy it, you would never have to convince me otherwise

 

[RDY4WAR]

I'd probably buy it too. I know you said you wouldn't know where to start with a drag racing specific oil but if you had to take a shot at it, what would you choose? Say if it was a 350ci V8 with reverse cooling, OEM bearing clearances, oil temp staged is 130*F and 160*F at the end of the run not exceeding 180*F on idle back to the pits, total run time from lane to return to pit area just 3-3.5 minutes, 6000 max rpm, oil changed every 4 races or about 50 passes. Very different environment than the everyday passenger car.

 

[SonofJoe]

Okay. You lost me at 'reverse cooling'! As Shannow & other BITOGers know well, I don't do nuts & bolts stuff. The last time I wielded a spanner in anger was forty years ago!

That said, it sounds from what you say, because of the reverse cooling system you employ, that your oil doesn't actually get that hot (180F or 82C). Notwithstanding that the oil will temporarily get somewhat hotter as it traverses the bearings, this is very moderate indeed. Even the lowliest of Group I oils could easily contend with this level of heat for a few minutes at a time.

I guess an appropriate question to ask would be how fast do you want to go and how far are you prepared to compromise engine life?

If your priority is wear (especially cam & tappet wear) then your priority should be to use a heavy oil containing not a lot of shearable VII; something like a 'tight' 20W50 for example. I used to get paid to sell additives and yes there's a lot you can do to counter wear with Zinc & Moly. However, any formulator worth his salt will tell you that, in terms of anti-wear, there's no substitute for non-shearable high viscosity & the presence of some genuinely heavy base oil in the blend. By all means slap in a goodly amount of Zn & Mo on top but go heavy! BTW, it won't matter what type of ZDDP you use at these kind of temps as both will be well above their respective activation temperatures.

Of course heavy oils are 'power sappers' and directionally will slow you down. I suspect you will go a bit quicker if you put a 0W16 in the sump...but it's not going to be as kind to your engine!

 

[Shannow]

Following on from Joe...his hypothetical 10W20 will have an HTHs in the 2.9 range...and at 180F, your supply temperatures are pretty low, so the high shear rate viscosity is also going to be high...much more than 2.9.

Reverse cooling per Corvettes in the '80s, cooling the heads, then the blocks...it's a sensible use of forced convection. The old thermosyphon techniques had the bubbles and the hot water flow the same way..

Need some AW additive in case things get closer than you wanted.

Don't need huge TBN, or extended oxidative stability...bar sitting a few months between accumulated races.

 

[RDY4WAR]

Right. Reverse cooling is cooling the heads first. Even if I manage 200 passes per season, that's all of 50 miles of wide open throttle plus idle time to and from the pits. Power is more of a concern than wear.

 

[Gokhan]

My favorite oil blender is ExxonMobil. They offer PAO-based oils with some of their Mobil 1 products. Nothing really matches PAO in both regular driving and racing. Their additive company Infineum is also the best in additives. They are the makers of the legendary TGMO 0W-20 SN as well.

This said, they offer a whole range of options for racing and towing. See their racing and towing catalog guide.

https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-racing-product-guide.pdf

It sounds like you want the Mobil 1 Racing 0W-30.

* HTHSV = 3.3 cP. So, you get the maximum horsepower (less viscous oil drag).

* It's PAO-based. PAO has by far the lowest friction coefficient (way lower than anything else) and least wear of all base oils. It also offers excellent viscosity index and excellent resistance to oxidation. It really makes a big difference in the overall quality, performance, and protection of the oil.

* Extremely high levels of ZDDP with 1750 ppm P and 1850 ppm Zn. It appears that it has two different compounds of ZDDP according to the MSDS.

* Extremely high levels of organo moly - sulfur complex with 1600 ppm moly (Mo).

https://bobistheoilguy.com/forums/ubbthreads.php/topics/2143222/new-mobil-1-racing-0w30-voa

Unless you need an high-HTHSV oil, you can't go wrong with it for racing applications. Otherwise, pick an oil with higher HTHSV from the racing and towing catalog guide. Note that not all are PAO-based or mostly PAO-based. Check the MSDS. Amsoil also offers PAO-based racing oils.

 

[Onetor]

You mentioned molybdenum. Try Redline if you really like moly and have $$$$$$. Best of luck in your endeavors.

 

[RDY4WAR]

I've considered Red Line. The Mobil 1 Racing 0w30 is a consideration as well.

Does moly and ZDDP offer friction reduction benefits even when not in boundary area lubrication?

 

[Gokhan]

Originally Posted by RDY4WAR
I've considered Red Line. The Mobil 1 Racing 0w30 is a consideration as well.

Does moly and ZDDP offer friction reduction benefits even when not in boundary area lubrication?

Boundary-lubrication regime, yes. Mixed-lubrication regime, yes. Hydrodynamic-lubrication regime, no.

 

[RDY4WAR]

Originally Posted by Gokhan
Originally Posted by RDY4WAR
I've considered Red Line. The Mobil 1 Racing 0w30 is a consideration as well.

Does moly and ZDDP offer friction reduction benefits even when not in boundary area lubrication?

Boundary-lubrication regime, yes. Mixed-lubrication regime, yes. Hydrodynamic-lubrication regime, no.


Gotcha. Thanks.

During hydrodynamic lubrication, I'm assuming the base oil plays a bigger factor in friction than the additive package?

 

[Gokhan]

Originally Posted by RDY4WAR
Originally Posted by Gokhan
Originally Posted by RDY4WAR
I've considered Red Line. The Mobil 1 Racing 0w30 is a consideration as well.

Does moly and ZDDP offer friction reduction benefits even when not in boundary area lubrication?
Boundary-lubrication regime, yes. Mixed-lubrication regime, yes. Hydrodynamic-lubrication regime, no.
Gotcha. Thanks.

During hydrodynamic lubrication, I'm assuming the base oil plays a bigger factor in friction than the additive package?

In the hydrodynamic-lubrication region, the minimum oil-film thickness (MOFT) is greater than the surface roughness. Therefore, any film layer deposited by the additives should play no role in the friction. The friction is only determined by the load/(RPM*viscosity) parameter. (The load is the contact pressure between the moving parts.) However, one can argue that the additives can shift the MOFT required for hydrodynamic lubrication, as the film layer affects the surface roughness. In other words ZDDP and moly can increase the value of the load/(RPM*viscosity) parameter at which hydrodynamic lubrication fails and mixed lubrication occurs.

 

[PeterPolyol]

Originally Posted by Gokhan
My favorite oil blender is ExxonMobil. They offer PAO-based oils with some of their Mobil 1 products. Nothing really matches PAO in both regular driving and racing. Their additive company Infineum is also the best in additives. They are the makers of the legendary TGMO 0W-20 SN as well.

This said, they offer a whole range of options .... PAO has by far the lowest friction coefficient (way lower than anything else) and least wear of all base oils. It also offers excellent viscosity index and excellent resistance to oxidation. It really makes a big difference in the overall quality, performance, and protection of the oil.


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