In my recent chamber refit I changed the oil but didn't do a self-pump of the fresh oil. I just ran the new oil - and also didn't bake the trap that sits right on top of it.
I just had a quick look at it, a 'routine' check - no concerns with the way the pump is running - and saw this brown goo where not so long ago there was nice fresh oil.
I am presuming that the oil already had soaked up its full load of water vapour when I put it in, then when it got hit with the output of the chamber and the trap I have ended up with an emulsion for oil because I didn't do a 'self-pump'.
Not sure this is very good! Or maybe it is just benign. I don't really have enough experience to know. I've left it pumping the trap for now, with ballast on. Any other comments/warnings welcome. I can change it again, but it'll be a bit of an awkward fiddle.
[Sorry for the file size - I shrank it but if I tried to upload anything but the original, it came up with an error 'cannot determine the size of the image'.]