dnewton3
Staff member
There are several things to glean from a UOA. They are a direct view of the lube health, and an indirect view of the equipment health. But do not confuse the topics of inputs and outputs, or the concept of properties and characteristics.
Let's go back to basics here guys.
Everything is geared towards wear reduction when it comes to lubes. Yes, oil does other things such as control temps, etc. But the MAIN thrust is wear reduction. Why have additives? To make the lube more servicable for a longer period of time. EVERYTHING is geared towards wear reduction. Want to control contamination? Fine. The goal of detergents is to keep the engine clean to reduce oxidation build up that could hamper return oil flow. Dispersents are supposed to keep soot/insolubles small to reduce wear. Want low fuel contamination? Fine, that helps keep the oil from thinning, which means you're trying to avoid wear. Get it? The theme is wear reduction. The same can be said for TBN; you can have a low TBN and low TAN, and if the wear is not being affected, then all is well. The job of the oil is to reduce wear. Some additives are there to directly affect the wear rates, other additives are there to make sure the lube stays in service for a longer period of time. But the GOAL of oil is to reduce wear. If you didn't need wear reduction, and only needed temperature control, then we'd have water or milk in the crankcase, wouldn't we ...
Think of it from the opposite perspective; would you continue to use a fluid that was within grade spec, but resulting in terrible wear rates?
It's surely accurate to say that oil vis will be offset between the thinning from shearing and the thickening from oxidation and insolubles. Concieveably you could have a lube never stray out of grade, but result in the VII package destroyed and the ox/insol levels growing. Certainly vis is something to keep an eye on. But that is ancilary to the topic of wear control and rates ...
The topic of thinning and thickening of the lube is only important if excessive wear rates are occuring. Viscosity is only an issue if the wear is not under control. I will give a nod at this point to the concept of vis in relation to mechanical design such as cam phasers. Having a lube with a vis grossly over or under spec may result in performance issues. Or, vis can be so grossly out of spec that start up is an issue (starter strain from extreme vis during cranking). But that isn't the case here, so we're going to ignore those topics.
In the HDEO world, PSD owners often nearly have a mental "stroke" (pun intended) when they see their 40 grade shear down to a 30 grade. But when you review the wear, everything is fine. Some guys that even choose to run a 30 grade in the PSD and don't see any wear acceleration as opposed to a 40 grade that is in spec. Conversely, I run a 10w-30 HDEO in my Dmax, and it thickened up to a 40 grade two years ago (presumably from oxidation); yet the wear rates were outstanding.
In short, grade is only important if it's affecting wear or performance. If not, it's moot.
To come full circle back to the OPs UOA:
This is a great UOA with excellent results. Can someone please point out to me the evidence viscosity resulting in poor wear control here, or the OPs complaint of performance issues?
Don't get caught up in the minutia ...
Let's go back to basics here guys.
Everything is geared towards wear reduction when it comes to lubes. Yes, oil does other things such as control temps, etc. But the MAIN thrust is wear reduction. Why have additives? To make the lube more servicable for a longer period of time. EVERYTHING is geared towards wear reduction. Want to control contamination? Fine. The goal of detergents is to keep the engine clean to reduce oxidation build up that could hamper return oil flow. Dispersents are supposed to keep soot/insolubles small to reduce wear. Want low fuel contamination? Fine, that helps keep the oil from thinning, which means you're trying to avoid wear. Get it? The theme is wear reduction. The same can be said for TBN; you can have a low TBN and low TAN, and if the wear is not being affected, then all is well. The job of the oil is to reduce wear. Some additives are there to directly affect the wear rates, other additives are there to make sure the lube stays in service for a longer period of time. But the GOAL of oil is to reduce wear. If you didn't need wear reduction, and only needed temperature control, then we'd have water or milk in the crankcase, wouldn't we ...
Think of it from the opposite perspective; would you continue to use a fluid that was within grade spec, but resulting in terrible wear rates?
It's surely accurate to say that oil vis will be offset between the thinning from shearing and the thickening from oxidation and insolubles. Concieveably you could have a lube never stray out of grade, but result in the VII package destroyed and the ox/insol levels growing. Certainly vis is something to keep an eye on. But that is ancilary to the topic of wear control and rates ...
The topic of thinning and thickening of the lube is only important if excessive wear rates are occuring. Viscosity is only an issue if the wear is not under control. I will give a nod at this point to the concept of vis in relation to mechanical design such as cam phasers. Having a lube with a vis grossly over or under spec may result in performance issues. Or, vis can be so grossly out of spec that start up is an issue (starter strain from extreme vis during cranking). But that isn't the case here, so we're going to ignore those topics.
In the HDEO world, PSD owners often nearly have a mental "stroke" (pun intended) when they see their 40 grade shear down to a 30 grade. But when you review the wear, everything is fine. Some guys that even choose to run a 30 grade in the PSD and don't see any wear acceleration as opposed to a 40 grade that is in spec. Conversely, I run a 10w-30 HDEO in my Dmax, and it thickened up to a 40 grade two years ago (presumably from oxidation); yet the wear rates were outstanding.
In short, grade is only important if it's affecting wear or performance. If not, it's moot.
To come full circle back to the OPs UOA:
This is a great UOA with excellent results. Can someone please point out to me the evidence viscosity resulting in poor wear control here, or the OPs complaint of performance issues?
Don't get caught up in the minutia ...
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