2011 Subaru Outback - Amsoil ATM 14,500 miles
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Welcome back, Bob! I thought you fell off the face of the earth!
dnewton3
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Wear is very low. Nothing but praise here.
TBN is nearly meaningless without knowing a TAN as well; likely not as big an issue as they state. When TBN is high, you dont' need a TAN. When TBN drops, then you need to also know TAN to know if the acids are up. TBN degredation is not linear; the degredation of TBN is not an assurace of acid presence nor immediate escalation
Ox is pretty much meaningless as well in this circumstance; too many issues that surround it to take this one number as gospel and make some errant determination. As I have learned, there is a lot that must go into this consideration, and the more I learned of it, the less I worry about it. I am NOT saying that heavy oxidation is always OK; that is not true. But it is difficult to determine real oxidation of the lube versus feigned oxidation due to chemistry components. I'm stating that unless you know the starting ox number, and the specific chemical makeup of the oil, then an artibrary number on a UOA has no point of reference. And, it's difficult to nail down a condemnation value on this as well. When you don't know the percentage of shift, and you have no idea where the Ox limit would be, it's a moot point to discuss. I have personally called Polaris Labs in the past and asked about this topic; they do have specific condemnation limits for lubes, but even then I have doubts about the ability to calculate condemnation points. But this is why I actually prefer an insoluble rating rather than Oxidation; it is a ranking based upon visual clues against a known standard (regardless of base stock), and takes not only oxidation but also other issues into consideration. In this report, we see that Ox was completely acceptable at 59 in the previous UOA, but then it's two points higher and totally ready for assured condemnation? What happend to the intermediate points in their rating legend? To go from what is "0" (perfectly normal) to a "4" (high severity at critical), with a shift of only 2 Ox points, seems dubious to me. Should there not be some intermediate graduation in there? Like I said; too much incidental suspicion and not enough hard facts when Ox is in a report like this. I question both the methodology and the condemnation limit.
I see no reason not to extend this lube out further; there is no significant intrusion of contamination and the wear is admirable. Perhaps get a TAN the next time to give perspective to the TBN; although I don't think it will be an issue and I suspect TAN would be fine given your driving pattern. To get a really decent ROI, the OCI must be extended though. Great showing for Amsoil and the engine; there is much more potential yet to discover in there. This is a newer vehicle, but warranty does not seem to be a concern to him (and I'm not saying it should or should not be; that is his determination to make). But given that extension of the OCI is currently being done, I think more is prudent here. The lube and engine can take it. The vehicle sees a majority of highway driving; 14k miles in 8 months would project out to 21k miles in a year. Easily within the Amsoil OCI limits of 25k miles or one year.
TBN is nearly meaningless without knowing a TAN as well; likely not as big an issue as they state. When TBN is high, you dont' need a TAN. When TBN drops, then you need to also know TAN to know if the acids are up. TBN degredation is not linear; the degredation of TBN is not an assurace of acid presence nor immediate escalation
Ox is pretty much meaningless as well in this circumstance; too many issues that surround it to take this one number as gospel and make some errant determination. As I have learned, there is a lot that must go into this consideration, and the more I learned of it, the less I worry about it. I am NOT saying that heavy oxidation is always OK; that is not true. But it is difficult to determine real oxidation of the lube versus feigned oxidation due to chemistry components. I'm stating that unless you know the starting ox number, and the specific chemical makeup of the oil, then an artibrary number on a UOA has no point of reference. And, it's difficult to nail down a condemnation value on this as well. When you don't know the percentage of shift, and you have no idea where the Ox limit would be, it's a moot point to discuss. I have personally called Polaris Labs in the past and asked about this topic; they do have specific condemnation limits for lubes, but even then I have doubts about the ability to calculate condemnation points. But this is why I actually prefer an insoluble rating rather than Oxidation; it is a ranking based upon visual clues against a known standard (regardless of base stock), and takes not only oxidation but also other issues into consideration. In this report, we see that Ox was completely acceptable at 59 in the previous UOA, but then it's two points higher and totally ready for assured condemnation? What happend to the intermediate points in their rating legend? To go from what is "0" (perfectly normal) to a "4" (high severity at critical), with a shift of only 2 Ox points, seems dubious to me. Should there not be some intermediate graduation in there? Like I said; too much incidental suspicion and not enough hard facts when Ox is in a report like this. I question both the methodology and the condemnation limit.
I see no reason not to extend this lube out further; there is no significant intrusion of contamination and the wear is admirable. Perhaps get a TAN the next time to give perspective to the TBN; although I don't think it will be an issue and I suspect TAN would be fine given your driving pattern. To get a really decent ROI, the OCI must be extended though. Great showing for Amsoil and the engine; there is much more potential yet to discover in there. This is a newer vehicle, but warranty does not seem to be a concern to him (and I'm not saying it should or should not be; that is his determination to make). But given that extension of the OCI is currently being done, I think more is prudent here. The lube and engine can take it. The vehicle sees a majority of highway driving; 14k miles in 8 months would project out to 21k miles in a year. Easily within the Amsoil OCI limits of 25k miles or one year.
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