Percentage wise, what percent of listed viscosity is acceptable? If the oil is listed as a 220 Vis oil should it be within 10%? 20%?

Thanks
Dick

Dick,

Listed oil viscosities are by definition plus or minus 10%. This is for new oil obviously. We sample incoming oil for properties and use the actual as the baseline for trending.

Ken Culverson - CMRP

+/-10% was given by OEM'S for new oil, however the user defined limits may go up to +20% to -10% it depends upon the aplication & sensitivity of your unit

quote:

Originally posted by Dick Kramek:
Percentage wise, what percent of listed viscosity is acceptable? If the oil is listed as a 220 Vis oil should it be within 10%? 20%?

Thanks
Dick

Dick,
The acceptablity depends on the criticality of the machine its in use, however +-10% from the reference oil viscosity is the acceptablity we use for most of our critical machines.
Also its very important to identify the cause of the viscosity change and rectify the causes.

Regards
Mohammad

Depends on the nature of the question at hand. If it pertains to the value versus the minimum allowable limit for a machine application - zero tolerance is acceptable for lower viscosity.

If you are talking about vis. versus the ISO grade, should be 10%+/- and no more to retain the grade value.

So, specifically what are you asking about?

I have a question ?

How the viscosity is tested?

usually we test viscosity at room temp and then correlate to 40 degC. If RT is different at different test times then it can induce errors.

Also different test equipment have diffrent parameters affecting the readings.

A collective trendeable approach would be better when taking a decision to change oil of courese +/- 20% should be a good limit.

correct me if am wrong...