Originally Posted by kschachn
Originally Posted by Alex_V
The first UOA I've done on an OM617 or this oil - very pleased! Also reaffirms my hunch that 40 weights aren't a necessity in these engines like a lot of the owners preach. This OCI had a pretty varied operation schedule - lots of short trips, 1000+ miles of 70-80 MPH highway running, and a few stints of very spirited backroad running.
You do realize however that since this oil carries MB-Approval 228.31 has a minimum HTHS of 3.5? As a result the difference between a 30-grade and a 40-grade designation is a bit meaningless in this instance.
Rotella calls this oil "low HTHS" but that is in reference to some of their other oils and for some of the competition, it's not exactly low HTHS in the overall scheme of things related to passenger car diesel oils.
+1.
Straight 30wt oils have always been allowed in certain temperature ranges.
The matter of 40wt oils is more about getting the right diesel-specific add pack, and a good level of ZDDP in there for these (somewhat) flat tappet cams.
Im interested to see how low the soot loading is for this duration.