RPVOT test Results

What brand of the new oil?

Andy Sitton

I would not call it normal, but I would not panic either. It is known that original RBOT (or better RPVOT) value often drops after the oil is in use, and than stabilize. In you case, this drop is maybe too drastic. However, you might re-test it more often, and test and track AN. As long as the AN is low, the oil is fine. Next time you take a sample make sure the oil is clean and dry before you send it to a lab, because contaminants can interfere with the test and yield a false negative result. I have seen this happen.

Please do the other tests also like viscosity,TAN etc...If these are within limits.
I don't see any problem for you to continue with the same oil.But you have to monitor the oil frequently.

This seems like a heck of a drop to me. Turbine oil is expected to last a long time. The fact that 60% of the life may be gone after one year would have me questioning the brand and type of oil that is being used in the application. There is a significant cost in replacing all of that oil every two years as opposed to every five. As everyone else has said continue to sample and establish a trend. This should be a concern and you should watch this closely.