Originally Posted By: Jaybird
The motorcycle crowd has their unfounded moly scares, and the block engine guys have their unfounded zinc scares. The moto guys think that any moly content will hose up their clutch system, which is an unfounded assumption.
Busting out the ad hominems. I'm scared now.
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The fact is that ZDDP content is not the way to judge the integrity of an oil. Studies have proven that there are many types of chemicals and compounds that interact quite well with ZDDP, and tend to improve or enhance the protective film that ZDDP offers. Some of the car guys caught onto the fact that when ZDDP levels seem to be lowering, there seemed to also be a rise in boron content. So immediately the car guys seem to think that if there is a drop in ZDDP, then there must be an accompanying rise in Borate level.
But what the car guys fail to realize, or have not researched, is that there are other products that are already being used that can enhance, or even replace the ZDDP content of an oil, yet still provide the same or better protection.
Many of these items not detectable with normal elemental analysis.
The chief reason for using ZDDP as a yardstick is because it is a known quantity and is easily detected. It's pretty well established that if the concentration is at a certain point, it will adequately protect a pushrod valvetrain. Even if a certain oil has ashless AW agents that are undetectable, how do we know they are in a high enough concentration for pushrod engines?
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I have yet to see any SAE papers referenced that explain that we need ZDDP, per se, and I am full aware of it's worth. Although I have seen lots of data that suggests there are many different things that are showing to interact very well with ZDDP. And these synergistic reactions between zinc and other elements or compounds are what allows the formulator to provide a quality fluid that is not dependent on any particular level of ZDDP as a benchmark. In fact, if you give a look at the info JAG provided, you will see that oil can be formulated with no zinc at all, and perform on par with a high zinc content fluid.
I read the Crompton paper too. Looks like everything except for imidazolidine thione and phenolic borate suck without some level of ZDDP present to help them.
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It makes all the difference in the world. If the taxi engines used roller lifters or overhead cams, then they can run on pretty much anything.
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What sort of study can we read determining that there needs to be a high rate of ZDDP?
Studies such as this one tend to show this not to be the case:
https://shop.sae.org/technical/papers/952344
I gather from this paper that the benefit of higher ZDDP was attributed to the fact that higher rates increased the oils ability to withstand oxidative thickening, and not with it's prowess as an AW film.
I only refed. that paper because they found that there was not significant difference in performance between higher dosed oil and lower ZDDP oil. They concluded the higher ZDDP level helped with oxidative thickening more than anything. Which makes sense, as formulators take advantage of the great job ZDDP does in fighting acidity.
Once again, no mention is made of the valvetrain design in the above study, which seemed primarily focused on cat life anyway.
I'd like to think that I've got an open mind, and that the newer oils are better for everything, but that remains to be proven, IMO. UOAs and engine teardowns will ultimately determine if the new low-SAPS oils (designed for OHC engines) are up to snuff.
- Scott
The motorcycle crowd has their unfounded moly scares, and the block engine guys have their unfounded zinc scares. The moto guys think that any moly content will hose up their clutch system, which is an unfounded assumption.
Busting out the ad hominems. I'm scared now.
Quote:
The fact is that ZDDP content is not the way to judge the integrity of an oil. Studies have proven that there are many types of chemicals and compounds that interact quite well with ZDDP, and tend to improve or enhance the protective film that ZDDP offers. Some of the car guys caught onto the fact that when ZDDP levels seem to be lowering, there seemed to also be a rise in boron content. So immediately the car guys seem to think that if there is a drop in ZDDP, then there must be an accompanying rise in Borate level.
But what the car guys fail to realize, or have not researched, is that there are other products that are already being used that can enhance, or even replace the ZDDP content of an oil, yet still provide the same or better protection.
Many of these items not detectable with normal elemental analysis.
The chief reason for using ZDDP as a yardstick is because it is a known quantity and is easily detected. It's pretty well established that if the concentration is at a certain point, it will adequately protect a pushrod valvetrain. Even if a certain oil has ashless AW agents that are undetectable, how do we know they are in a high enough concentration for pushrod engines?
Quote:
I have yet to see any SAE papers referenced that explain that we need ZDDP, per se, and I am full aware of it's worth. Although I have seen lots of data that suggests there are many different things that are showing to interact very well with ZDDP. And these synergistic reactions between zinc and other elements or compounds are what allows the formulator to provide a quality fluid that is not dependent on any particular level of ZDDP as a benchmark. In fact, if you give a look at the info JAG provided, you will see that oil can be formulated with no zinc at all, and perform on par with a high zinc content fluid.
I read the Crompton paper too. Looks like everything except for imidazolidine thione and phenolic borate suck without some level of ZDDP present to help them.
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- What vehicles and engines were in the fleet of 1991 cars in the paper you cite as evidence that ZDDP isn't required?
It makes all the difference in the world. If the taxi engines used roller lifters or overhead cams, then they can run on pretty much anything.
Quote:
Quote:
What sort of study can we read determining that there needs to be a high rate of ZDDP?
Studies such as this one tend to show this not to be the case:
https://shop.sae.org/technical/papers/952344
I gather from this paper that the benefit of higher ZDDP was attributed to the fact that higher rates increased the oils ability to withstand oxidative thickening, and not with it's prowess as an AW film.
I only refed. that paper because they found that there was not significant difference in performance between higher dosed oil and lower ZDDP oil. They concluded the higher ZDDP level helped with oxidative thickening more than anything. Which makes sense, as formulators take advantage of the great job ZDDP does in fighting acidity.
Once again, no mention is made of the valvetrain design in the above study, which seemed primarily focused on cat life anyway.
I'd like to think that I've got an open mind, and that the newer oils are better for everything, but that remains to be proven, IMO. UOAs and engine teardowns will ultimately determine if the new low-SAPS oils (designed for OHC engines) are up to snuff.
- Scott