Originally Posted By: Pablo
Originally Posted By: dnewton3
The oxidation went way up; bizzare.
Originally Posted By: dnewton3
I appreciate the chemistry lesson. But I'm just about convinced that oxidation is (nearly) a moot point. Only if it were SERIOUSLY shifted in an VERY EXAGGERATED manner, would it mean anything at all. Regardless of base stock.
As I clearly stated watch for the trend.
Ok - I get that. But it's useless info unless one could establish that a condemnation limit were definable. A "trend" is only an acknowledgement of a shift in direction. It does not speak to where a limit would be at. And it seems that limits would be perhaps unique to each lube utilized; as noted by several of you, one would need a VOA for contrast. And even then, it does not tell you how high the tolerace would be for delta ox or delta vis.
I would disagree, Pablo, that a "trend" is the indication of anything more than anecdotal evidence in this topic. You state to "watch for the trend". To what end??? That's not helpful. Let me play out an analogy ...
I tell my teenage son to go down to the market on Green street and get a newspaper. I tell him to NOT enter the "XXX" video store at the end of Green street. I watch him walk down Main street, and then turn onto Green street. A "trend" has occured; he shifted direction. Further, he walks down Green street, and then walks into the Subway sandwich shop and gets a Coke, then walks out and into the hardware store to look at tools, and finally goes into the market to get the paper. His "trend" continued down the street with each stop, but none were at the condematnion point (the XXX-video at the end of the street). TRENDS are worth noting, but unless you set a condemnation limit, they are meaningless, are they not? They can point to a potential issue, but they are not the sole reason to stop some action. They may never reach condemnation. They may reverse themselves with outside influence. They may stagnate. Trends indicate direction; condemantion points indicate location/postion. Trends indicate observation is warranted; condenmation limits indicate action is required. Two differnt concepts.
I am certainly a proponent that one of two things would indicate an OCI is warranted:
1) multiple criteria are tracked, and reasonable condemnation limits are in place, and more than one characteristic crosses over by small or moderate margin
2) multiple criteria are tracked, and reasonable condematnion limits are in place, and one characteristic goes grossly over a limit
I would NOT OCI simply because my TBN got below 2.0, when the wear rates were good, the insolubles were low, the contamination (fuel, dirt, coolant) were low or non-existent, etc. Just because TBN may cross an artibrary threshold, does not warrant an OCI. Another excellent example would be the famous Dmax Cu exposure issue. I have never said that the presence of Cu in extreme magnitudes automatically warrants an OCI; I have only said that the presence of Cu in such high concentrations can mask other potential issues, and that one must decide to put up with the high Cu for a few OCIs (running "blind" to other events), or choose to do several OCI flushes to rid the system of the excess Cu.
If I had a great UOA report, but the coolant or Si were stupid high, and could be confirmed (coolant loss in tank or discovered leak in air-intake tract), then I'd OCI as a matter of getting the junk out, fix the issue, and then start over with a fresh OCI/UOA. Regardless of how good other UOA criteria were, the really high concentration of contamination would warrant an OCI IMO in cases like this.
So all that in mind, we have a couple of UOAs here in this thread with different Ox numbers because of different base stock configurations. OK - fine. But how much shift in Ox or vis would indicate some threshold worthy of considering action? 75% of the base number? 75% of a shift towards an artibrary target?
Like I said, the more I look at it, it's moot. We are missing two very important pieces of the puzzle to make a clear decision:
1) we don't know starting OX values from these loads
2) we don't have the ability to clearly define where condemnation is, even after we recognize a trend
What I care about is wear. If the Ox were 10 or 100, would be of no consequnce if the wear rates stayed (nearly) flat. Only if I saw significant escalation in wear rates would I become concerned, and look for the root cause indicators in other parts of the UOA. This is not without merit; the SAE study acknowledges this, and my large database also has statistical evidence to confirm it's a sound premise.
Again - thanks all for the chemistry lesson.
