Everyone including myself have their opinions on the subject but what does Cummins say about Oil Analysis? Just an FYI.
From the Cummins Recreational Vehicle Quick Reference Guide on all of the engines I have seen:
"Oil Analysis
Oil analysis, as a method to extend drain intervals, is NOT recommended. Different methods of measuring soot, lack of correlation among testing labs, and differing driving patterns and idle time are the basis of the recommendation.
Oil analysis can be useful in detecting contaminants such
as dirt."
