Originally Posted By: WobblyElvis
I have paid for the TBN test from Blackstone on several occasions. The results have come in as low as "1.0" and blackstone has still recommended I extend the OCI another 1,000 miles. Every OCI I have used has been in excess of the oil life monitor and wear metals have been below unit averages. The TBN has been of no use or consequence in determining the OCI. Insolubles has never exceeded 1/2 of the recommended limit.
However, when the OCI went as high as 15,000 miles, I found the oil filter loaded with carbon and I was unable to see any light through the filter media. Carbon/sludge was building up in the folds of the filter media near the end caps yet lab results indicated TBN and insoluble were well within limits. For this reason I do value the TBN or insoluble numbers provided by Blackstone very highly but I do look closely at the old filter.
If the additives in the oil have depleted to the point of not holding contaminants in suspension, yet lab results indicate there is no problem, what use are these test results?
There's also the issue of TAN, which when it gets high enough will cause bad things to happen despite still-high TBN; the entire condition of the oil has to be examined, not just one or two parameters. So in your case the oil's additive package (TBN) was fine, but there were other things going on that were causing the carbon - was it cleaning, or was the oil failing? Did you get a TAN and what were the other indicators of the oil's condition?
I have paid for the TBN test from Blackstone on several occasions. The results have come in as low as "1.0" and blackstone has still recommended I extend the OCI another 1,000 miles. Every OCI I have used has been in excess of the oil life monitor and wear metals have been below unit averages. The TBN has been of no use or consequence in determining the OCI. Insolubles has never exceeded 1/2 of the recommended limit.
However, when the OCI went as high as 15,000 miles, I found the oil filter loaded with carbon and I was unable to see any light through the filter media. Carbon/sludge was building up in the folds of the filter media near the end caps yet lab results indicated TBN and insoluble were well within limits. For this reason I do value the TBN or insoluble numbers provided by Blackstone very highly but I do look closely at the old filter.
If the additives in the oil have depleted to the point of not holding contaminants in suspension, yet lab results indicate there is no problem, what use are these test results?
There's also the issue of TAN, which when it gets high enough will cause bad things to happen despite still-high TBN; the entire condition of the oil has to be examined, not just one or two parameters. So in your case the oil's additive package (TBN) was fine, but there were other things going on that were causing the carbon - was it cleaning, or was the oil failing? Did you get a TAN and what were the other indicators of the oil's condition?
