TBN Limits

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I believe bitog'ers say 3.0 tbn change the oil and Blackstone says 1.0

Please educate me on tbn condemnation so I understand.I am seeing between 5.2 and 5.8 tbn on 20k Schaeffer 9000 5w40 and don't plan on changing oil anytime soon
Thanks!
 
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I say at 2 you plan the oil change and at 1 you do it very soon.

But unless you have a diesel with many gallons of oil, you will most of the time not be looking at a UOA to see if you should change the oil. You sample and change.
 
Well that's a very good TBN. However what is the total acid number?? The condemnation limit is according to some people where TBN is equal to TAN. While others suggest TAN a tad higher than TBN can still be viable for a little while. Plus, what is the oils viscosity at 100°C?? Is it within it's proper range?? Or has it sheared well out of grade?? Also what if any other containments are present?? Fuel or possible antifreeze?? Sodium with potassium present would be an indicator of antifreeze present in your oil.
 
Originally Posted By: bbhero
Well that's a very good TBN. However what is the total acid number?? The condemnation limit is according to some people where TBN is equal to TAN. While others suggest TAN a tad higher than TBN can still be viable for a little while. Plus, what is the oils viscosity at 100°C?? Is it within it's proper range?? Or has it sheared well out of grade?? Also what if any other containments are present?? Fuel or possible antifreeze?? Sodium with potassium present would be an indicator of antifreeze present in your oil.


13.17 and 13.84 cst 2 diff trucks, the bypass system makes it a total of 11 gallons per truck capacity no fuel dilution no antifreeze or sodium all other where metals are in check
 
I used to have a couple Volvos and their lowest TBN was either 1 or 1.5 as the cut off. Detroit Diesel says one third of the virgin TBN or 3.0 using either method (ASTM D4739 or D2896). That goes tor your Series 60s or my DD13 engine. I don't recall either Volvo or Detroit mentioning TAN in the consideration.

I had several UOAs where TAN far exceeded TBN but it was a non issue. A few of them showed a few more PPM of bearing metals but still in the single digits and no harm as far as I was concerned.
 
I get my oil analyses done at Polaris, and they say to change at 35% of virgin TBN. They don't look at TAN at all.
 
3 Taxi cab UOA's

Shannow posted that yesterday. If you were only going by TBN of 2-3 or greater, you'd be using those 3 sets of OCI's well past their point of failure. TAN had crossed TBN well before the 2-3 range. TBN by itself is not necessarily helpful. In this case failure around TBN's of 4.
 
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