I also have a York YT 500 ton chiller and Johnson tech is telling me that there is no possible way that oil can cross with the refrigerant in the seal is that correct. I ask because I am loosing oil into the refrigerant and I have already checked the eductor and lines, oil sump temp, refrig dryers (changed), oil filter and purge unit. Please help this is going to be our primary machine and our new machine is to be installed so our older backup is to be removed. We need to figure this out.