Agreed. Sounds like water. How often do you perform lube oil analysis. The water should show up in the analysis.
Also, don’t know about your configuration but do you have any lube oil cross tie lines with other engines that the blind mentioned does not isolate. If so, you may want to check the cross tie isolations.
Again – don’t know about your configuration but I know of facilities that ended up with fuel in the lube oil – is that a possibility at your facility.