So, I was reading the Lubrizol HyperZDP Report and came across an interesting graph on page 16:
http://www.gf-5.com/uploads/File/Hyper_ZDP_System_Powerpoint.pdf
It shows that the TBN/TAN crossover for both reference oils, with or without HyperZDP, is around 3,400 miles.
At one point, I recall one "expert" on this site mention that once an used oil's TAN value exceeds TBN, it means the lubricant is at or nearing the end of its service life.
I have learned from two studies for diesel oils that the crossover point for TBN/TAN is indicative of when acids in the engine will begin to significantly increase and there have been past links between corrosive wear and strong acid presence in oil:
Quote:
Determination of service interval with respect to
TBN/TAN levels using this method can be attributed to
the intersection of the two corresponding levels. This
intersection has been chosen empirically, however it
can be seen from Figure 1 that after the intersection of
the two values the plateau level of the TAN begin to
significantly increase as the levels of strong acids
within the oil rapidly increase.
It is therefore suggested that the presence of a low
rate of increase in TAN is therefore indicative of
adequate engine protection from corrosive effects of
strong acids. Whether this intersection absolutely
correlates to the point at where a critical increase in
corrosive wear takes place is beyond the scope of this
work, however, from the understanding of the nature of
acid and base ionic species within the oil it can be
suggested that the level of corrosive wear will be linked
to the concentration of strong acids available within the
oil.
The maximum service interval capability from the
vehicle for Oil D is 11,500km (figure1) and the
TAN/TBN intersection is 3 mgKOH-1. Operation of the
dynamometer test generates an intersection at the same
TAN/TBN level (figure 2), occurring at 70 hours. This
suggests a relationship between the oil behaviour on the
dynamometer cycle and that observed in the vehicle
test.
A relationship can also be seen, in the vehicle trial,
between the fresh oil TBN value and maximum drain
capability determined by the intersection of the TAN
and TBN values (figure 3). This indicates that the
primary factor involved in drain capability when using
high sulphur fuels is the TBN of the fresh oil. However,
this does not suggest there is no effect from the TBN
retention quality of the oil, which requires further
investigation.
CONCLUSION
This study highlights a relationship between fresh
oil TBN and drain capability when using high sulphur
fuels and that the TAN/TBN intersection is a justified
metric for determining the maximum drain capability of
an oil in high sulphur fuel areas.
It can also be concluded that there exists a potential
relationship between the dynamometer cycle and a
typical vehicle drive cycle with respect to TAN/TBN
and high sulphur fuel. This conclusion generates the
need for further investigation to determine whether
differing abilities of oils for TBN retention is also a
contributory factor and whether this is reflected when
using different oil qualities.
Another study also presented a similar opinion:
Quote:
(TAN) and total base number (TBN) measurements were used to track the change in acidity of the fluids using the RULER method and ASTM Standard Test Methods D664 and D4739. Normally, the rate of depletion of the additives is an indication of end of oil life. This is indicated by a crossover of the TAN and TBN values.
http://docs.google.com/viewer?a=v&q=...LcOQDFk4qCZJT3w
On the other hand, another study highlights in its conclusion that TBN/TAN crossover is not a reliable indicator of relative lubricant performance:
http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2008/session10/deer08_watson.pdf
So here are my questions:
1) Is the information in those studies applicable to gasoline applications?
2) Considering that fuel quality has been noted to be a concern in the US, is sulphur responsible for poor fuel quality in the US?
3) Is TBN/TAN crossover a reliable indicator of when lubricant performance will begin to deteriorate, and corrosive wear will begin to take place?
4) Could Mobil 1's high iron readings be related to corrosive wear taking place due to users running their oil until TAN values far exceed TBN remaining?
5) From the Lubrizol study, it showed a TBN/TAN crossover point of around 3400 miles. So is that a safe, conservative interval for most conventional oils?
Thanks!
http://www.gf-5.com/uploads/File/Hyper_ZDP_System_Powerpoint.pdf
It shows that the TBN/TAN crossover for both reference oils, with or without HyperZDP, is around 3,400 miles.
At one point, I recall one "expert" on this site mention that once an used oil's TAN value exceeds TBN, it means the lubricant is at or nearing the end of its service life.
I have learned from two studies for diesel oils that the crossover point for TBN/TAN is indicative of when acids in the engine will begin to significantly increase and there have been past links between corrosive wear and strong acid presence in oil:
Quote:
Determination of service interval with respect to
TBN/TAN levels using this method can be attributed to
the intersection of the two corresponding levels. This
intersection has been chosen empirically, however it
can be seen from Figure 1 that after the intersection of
the two values the plateau level of the TAN begin to
significantly increase as the levels of strong acids
within the oil rapidly increase.
It is therefore suggested that the presence of a low
rate of increase in TAN is therefore indicative of
adequate engine protection from corrosive effects of
strong acids. Whether this intersection absolutely
correlates to the point at where a critical increase in
corrosive wear takes place is beyond the scope of this
work, however, from the understanding of the nature of
acid and base ionic species within the oil it can be
suggested that the level of corrosive wear will be linked
to the concentration of strong acids available within the
oil.
The maximum service interval capability from the
vehicle for Oil D is 11,500km (figure1) and the
TAN/TBN intersection is 3 mgKOH-1. Operation of the
dynamometer test generates an intersection at the same
TAN/TBN level (figure 2), occurring at 70 hours. This
suggests a relationship between the oil behaviour on the
dynamometer cycle and that observed in the vehicle
test.
A relationship can also be seen, in the vehicle trial,
between the fresh oil TBN value and maximum drain
capability determined by the intersection of the TAN
and TBN values (figure 3). This indicates that the
primary factor involved in drain capability when using
high sulphur fuels is the TBN of the fresh oil. However,
this does not suggest there is no effect from the TBN
retention quality of the oil, which requires further
investigation.
CONCLUSION
This study highlights a relationship between fresh
oil TBN and drain capability when using high sulphur
fuels and that the TAN/TBN intersection is a justified
metric for determining the maximum drain capability of
an oil in high sulphur fuel areas.
It can also be concluded that there exists a potential
relationship between the dynamometer cycle and a
typical vehicle drive cycle with respect to TAN/TBN
and high sulphur fuel. This conclusion generates the
need for further investigation to determine whether
differing abilities of oils for TBN retention is also a
contributory factor and whether this is reflected when
using different oil qualities.
Another study also presented a similar opinion:
Quote:
(TAN) and total base number (TBN) measurements were used to track the change in acidity of the fluids using the RULER method and ASTM Standard Test Methods D664 and D4739. Normally, the rate of depletion of the additives is an indication of end of oil life. This is indicated by a crossover of the TAN and TBN values.
http://docs.google.com/viewer?a=v&q=...LcOQDFk4qCZJT3w
On the other hand, another study highlights in its conclusion that TBN/TAN crossover is not a reliable indicator of relative lubricant performance:
http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2008/session10/deer08_watson.pdf
So here are my questions:
1) Is the information in those studies applicable to gasoline applications?
2) Considering that fuel quality has been noted to be a concern in the US, is sulphur responsible for poor fuel quality in the US?
3) Is TBN/TAN crossover a reliable indicator of when lubricant performance will begin to deteriorate, and corrosive wear will begin to take place?
4) Could Mobil 1's high iron readings be related to corrosive wear taking place due to users running their oil until TAN values far exceed TBN remaining?
5) From the Lubrizol study, it showed a TBN/TAN crossover point of around 3400 miles. So is that a safe, conservative interval for most conventional oils?
Thanks!
