Thread: Oil analysis - why it is best to look at trends rather than absolute values.

In case anyone is interested... This work was prompted by some oil analysis results on clean oil which showed 0.5% soot when returned. I have since learn that even the most accurate (ASTM) method produces very rubbery results.

ScienceDirect - Tribology International : Thermogravimetric analysis of carbon black and engine soot—Towards a more robust oil analysis method

I am not saying that oil analysis should not be done, on the contrary. Just that it should be used to look at trends rather than absolute numbers.

e.g. it was found that many samples can have up to twice the soot levels that commercial oil analysis reports.

Yep, have seen that often and lab results vary from lab to lab, and some labs are more consistent than others.

The other thing I've found is to not use the labs for analysis, use them for raw data only, get someone that really knows to analyse the data.
There's a hell of a lot in it and a lot that can be gleaned, much, much more than I know and the techs at the lab are on such a tight time schedule they can't stop and really spot things.