I posted a similar question last year......Does anybody know of a percent of change in dielectric that tells you the oil's usefulness has expired? I see alot of diffent numbers out there, anywhere from .02% to a couple of percent. Neither one of those numbers really make sense to me. I sampled some oil of an over the road truck who changes their oil according to manufacturer's specs and I had a change in dielectric of around 6%. I would appreciated any input available.

I don't think that you will be able to base your decision of oil-change on the change of di-elctric constant.Metal prticles, carbon particles,moisture, fuel dilution- some factors have positive and others have negative effect on the Di electric constant.They may neutralize each other resulting in no change of di electric constant and you will not feel like changing oil.While actual situation is, oil needs to be rejected immediately from the point of view of both factors-one having increasing effect, the other having decreasing effect. So again I will say that it is dangerous to decide oil change on the basis of change in di electric constant

Hi,On the subject of dielectric analysis of oils
can you enlighten me as to any manufacturers of dielectric oil analysers.
We have several NI dual lubrisensors in use,[we wish to aquire more] but these units are no longer available,[apparently Northern Instruments Corp ,[US] sold their lubrisensor division to a german co two years ago, but no one knows of this company and the product has not re-appeared on the market.

I disagree about using dielectric to measure oil quality. Given the right amount of research you will be able to tell exactly what is causing the dielectric to go up or down. So it could not only be used as a quality sensor but also as a diagonostic device. Depending on which way the dielectric sways and how much, how quickly you will be able to to tell what is causing the problem and hopefully fix the problem before it becomes catastrophic.

John not sure of the site but in the past when I was researching the Lubrisensor on the internet I found a web page similar to this where people talk with each other about oil quality. From what I remember from the postings there was a German named man talking about how he sells them. I know if you do a search on the internet you will probably find what I am talking about. I will go through my notes and see if I can come up with the site for you.

John here is the contact info I have for the German place that sells a similar product:
Hans Neffgen
www.neffgengmbh.de
info@neffgengmbh.de

Other dielectric type sensors are from a company called BIC or Brookhaven instruments Corp.
Contact info:
Dr. Williams
1-631-758-3200
www.bic.com

Another company is CSI or Computational Systems Inc.
Contact info:
Marj Worley
1-865-675-2400
www.CSImeansReliability.com

Final company is Reliability Direct
www.reliabilitydirect.com
product name is OilCheck TMEH 1