VISCOSITY DROP IN OIL - HELP NEEDED

It could be a very sensitive case. I think you have to re-check with your system if there's no contamination made by machine leaking or human error in topping up the oil for the primary investigation. Then we shall go deep in more details.

thanks uniqueth for ur lkind asnswer. unique th I have checked each and every inch of the VRM. No leakages are present. Morever, we dont do any top up as the sealks are intact. There are no contaminations. We are surprised to be in such a situation.
kindly suggest

High shear can cause viscosity losing in some cases ... I'm not sure if your VRM is the plate bender?

How sure are you that your oil's starting viscosity was 460 cSt? Did you test it or just assemed it is 460?

Dear John

The oil viscosity was tested.

Dear Uniqueth
its not a plate bender. Mine is a UBE make VRM of Raw mill of Cement plant

Dear Shubrajit, for the lubricant to reduce viscosity by 25% the base fluid could have been damaged with heavier ends deposition, oil would appear dark and heat affected,
If the lubricant appears clean and normal than the base fluid could have beed increased by adding a polymer when blended that has sheared down in service or a lighter oil has been added,
As you did not mention heat damage and you are sure nothing was applied then the lubricant appears to have been reinforced by polymer when blended to achieve the correct viscosity with the subsequent reduction of viscosity occurring as the plymers shears as the lubricant is lubricating the application. Rob S

Hi,
will like to know about VI of fresh oil,is it blended with any polymer which get sheared upon usage.