we used ch-4,15w40 oil in our Power Generater oil analysis shows loss in viscosities @40&@100 about 3% for 200 HRS but the VI is remained unchanged there is no drop in flash point ,Can some one comment on these findings
Original Post
Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity
Replies sorted oldest to newest
No drop in flash suggests no fuel dilution.
VI is calculated from V40 and V100 and is sensitive to the accuracy of these two values, so would expect VI to be the less reliable result.
Drop of 3% anyway not significant at this time and may be due to slight polymer shear.
Soot value for these viscosities should be quite low(< 0.5%WT)(assuming engine is diesel)
VI is calculated from V40 and V100 and is sensitive to the accuracy of these two values, so would expect VI to be the less reliable result.
Drop of 3% anyway not significant at this time and may be due to slight polymer shear.
Soot value for these viscosities should be quite low(< 0.5%WT)(assuming engine is diesel)
Only other cause is thermal cracking, not normally applicable to most lube oil systems, because it requires prolonged high temperatures(i.e. in a heat transfer system)
Fageer,
Something else may have happened with the drop in TBN value after 2000hrs. Was the oil level very low - do you have a low oil alarm? Not sure if you also checked the TAN on the oil as well to see if there was a sudden increase in TAN.
Something else may have happened with the drop in TBN value after 2000hrs. Was the oil level very low - do you have a low oil alarm? Not sure if you also checked the TAN on the oil as well to see if there was a sudden increase in TAN.
Action is required when TBN drops below ~40% of the new oil. However you say that you have topped up with oil with lower TBN.
Fundamentally, you should be using an oil to a spec demanded by the engine say API CH4, this will normally provide a TBN ~10.
For an optimum engine life would not suggest reducing oil spec for any top ups.
2000 hours seems quite a long period anyway, depending on engine, oil quality and sump capacity.
Fundamentally, you should be using an oil to a spec demanded by the engine say API CH4, this will normally provide a TBN ~10.
For an optimum engine life would not suggest reducing oil spec for any top ups.
2000 hours seems quite a long period anyway, depending on engine, oil quality and sump capacity.
Viscosity decrease is only alarming above the range of above 15% .your case is very normal.
never top up with other oils having low TBN.
Always refer the OEM reommendation while doing something.
Hope this helps
never top up with other oils having low TBN.
Always refer the OEM reommendation while doing something.
Hope this helps
Guys,
the drop in 3% is just the error in the measurement method. Test again with the same operator, same laboratory, and same equipment as the first time, and it might get back to the original. Then you can start another Forum saying "how can that happen".
Just leave the oil alone. It is OK.
the drop in 3% is just the error in the measurement method. Test again with the same operator, same laboratory, and same equipment as the first time, and it might get back to the original. Then you can start another Forum saying "how can that happen".
Just leave the oil alone. It is OK.
Or:
"How can Otto34 fill 101 posts/reply's with this kind of information"
"How can Otto34 fill 101 posts/reply's with this kind of information"
Otto34 do you think 3mgKOH/g TBN value is ok for deisel engine oil !!?? What agood advice from double platinum member!!!
As said already, lower limits for TBN must be based on the value of the fresh oil. As an example, TBN drop can be considered abnormal at 50% and critical at 66%. It works for me.
In a way, you can see TBN as a tool that gives an idea of the level of active additive still doing their job (antiwear, antioxydant, slipping agent). Since TBN is an indicator, limits must be set by compairing TBN values with other parameters. If an additive does not offer proper protection, other oil parameters will be affected. For instance, oxidation, wear metals, tan and viscosity will probably start to go up. For my application, the phenomenon is obvious. This is a sign that something is going on. Studying the relation between TBN, viscosity and oxidation, while considering limits you already have for these parameters, might help you setting your TBN limits.
Anyone agrees?
In a way, you can see TBN as a tool that gives an idea of the level of active additive still doing their job (antiwear, antioxydant, slipping agent). Since TBN is an indicator, limits must be set by compairing TBN values with other parameters. If an additive does not offer proper protection, other oil parameters will be affected. For instance, oxidation, wear metals, tan and viscosity will probably start to go up. For my application, the phenomenon is obvious. This is a sign that something is going on. Studying the relation between TBN, viscosity and oxidation, while considering limits you already have for these parameters, might help you setting your TBN limits.
Anyone agrees?
Question: do any OEM's appear to be changing from the general limit of 15%? We are noticing in S.E. Asia that 10-15% (without the presence of fuel) is becoming the "norm" rather than the exception. andy.sitton@focuslab.co.th
quote:Originally posted by hardy:
Viscosity decrease is only alarming above the range of above 15% .your case is very normal.
never top up with other oils having low TBN.
Always refer the OEM reommendation while doing something.
Hope this helps
