If you are testing a turbine oil, suggest you run RULER to determine the level of anti oxidants and remaining in the oil. AO's protect the base oil form oxidation. Faster results, less expensive.
Ruler test only able test amine and phenolic additive right? If my oil have ZDDP and apply on steam turbine. I don think ruler test is necessary. Right?
Keep in mind that RPVOT or RBOT testing has quite a big spread in the results, sometimes as much as 25%. I would not rely on this test alone. Look at additive level and acid number also.