INFO for TAN

[buster]

When looking at TAN, consider the following:

Quote:
Testing for the TAN only provides useful info if you're talking about ATF, gear lube or hydraulic oil (many synthetics have significant TAN right out of the bottle).
For engine oils it's fine to just look at TBN with the following condemnation limits:

Labs using "ASTM D-4739" method like OAI or AVLube - TBN drops to 1/3* of baseline value...

Blackstone Labs - TBN drops to 1/4* of baseline value....

*Note that this method yields different cutoff values, depending on the initial TBN of the lube. I've found this makes sense, since by the time a 12 TBN oil gets down in the 4.0 range you tend to have a high solids level as well as some acidic components. By contrast if you start out with a 6-8 TBN you can go with a lower cutoff and you don't see any chemical wear effect on softer alloys containing Cu or Pb.



As we've seen, many VOA's of oils show a high TAN so this makes sense....

 

[Quattro Pete]

What is the source of this info?

 

[A_Harman]

This is interesting and timely, as I have just gotten an analysis back from Polaris Labs on my diesel Dodge. They recommend changing when TBN reaches 35% of virgin. That is close to the 33% quoted in the ASTM D4739 reference above.

 

[buster]

Source is Tooslick.

 

[tribocessive]

and then there is the famous vegas taxi stuff; fleet vehicles, idling on hot, dusty roads, with the ac on all of the time, and minimal freeway driving to burn off acids; fleet managers were reporting that they were expecting the M1 they were using to have tbn numbers hovering around 1.5 to 15-20k mi of oil service, etc; buster, when should i change my oil, big picture? TAN, TBN, particle count... isn't TAN supposed to indicate acid neutralizing ability ?

 

[buster]

Quote:
As for TBN retention, it is only a single parameter that provides an indication of the used oil condition. A reduction in TBN is an indication that the overbased detergent is doing its job by neutralizing acids that form as a result of combustion. TBN should be used in combination with other used oil parameters such as oxidation, nitration, TAN (Total Acid Number), ICP metals, D4684 MRV viscosity, and D445 kinematic viscosity to determine the overall condition of the used oil.

Finally, in our experience in severe-service Las Vegas field testing, Mobil 1 engine oil TBN levels typically do not drop below 2 for vehicles with 15,000 mile oil drain intervals. Furthermore, it is our experience that those oils tend not to drop any lower when we continue to 20,000 mile oil drains.

 

[tig1]

Originally Posted By: buster
Quote:
As for TBN retention, it is only a single parameter that provides an indication of the used oil condition. A reduction in TBN is an indication that the overbased detergent is doing its job by neutralizing acids that form as a result of combustion. TBN should be used in combination with other used oil parameters such as oxidation, nitration, TAN (Total Acid Number), ICP metals, D4684 MRV viscosity, and D445 kinematic viscosity to determine the overall condition of the used oil.

Finally, in our experience in severe-service Las Vegas field testing, Mobil 1 engine oil TBN levels typically do not drop below 2 for vehicles with 15,000 mile oil drain intervals. Furthermore, it is our experience that those oils tend not to drop any lower when we continue to 20,000 mile oil drains.



I personally have never worried about TBN and longer OCIs, but one member here describes the data from XM that you have presented as marketing and should be ignored, or at least that's how I preceived it.

 

[tribocessive]

i choose to put a lot of weight in what is stated in the las vegas taxi study; some of what happened there is either counterintuitive or the sign of an awesome oil; i'm never gonna stop asking myself what oil should i use and when should i change the oil? the indicators will continue to be scrutinized.