Still running trailers. Finishing up the winter season, but fewer overnight idles and regens. 50% towing, 50% deadheading. Polaris comments: Flagged data does not indicate an immediate need for maintenance action. Continue to observe the trend and monitor equipment and fluid conditions. Cylinder region metals (pistons, rings, liners etc.) are at a MODERATE LEVEL; OXIDATION is at a MODERATE level, which may be due to extended drain interval or high operating temperature. Viscosity is MODERATELY HIGH. Causes include contamination, oxidation, incorrectly identified viscosity grade, or adding a different viscosity grade to the component. Increased VISCOSITY is likely due to ELEVATED SOOT LEVEL. Soot is at a MINOR level and is not yet cause for concern. Monitor future samples for increasing levels. Elevated soot reduces combustion efficiency and may indicate varying load conditions, malfunctioning EGR, exhaust restriction, or a timing/air-to-fuel ratio imbalance. Base Number is SLIGHTLY LOW. As Base Number depletes, the ability to neutralize acids is diminished. Please provide the APPLICATION (transportation, off-highway, gas/oil field, industrial, marine, mining, automotive, etc.) for a more thorough analysis. Lubricant and filter change acknowledged. The major concern on the last oil analysis was the high Iron level, which I attributed to using the Better Diesel FBC fuel additive. So I didn't use it at all during this OCI. The apparent Iron wear rate decreased from 7.95 to 5.44 ppm/kmile, a decrease of 32%. So knowing this, I think I will go back to using the FBC, and assume the actual Iron wear rate is ~30% less than shown in the UOA. Soot of 2.2% is about what I would expect: 10% fewer miles on this OCI, so 10% less soot. It seems to behave linearly. Once again the KV100 has increased into the mid-17's. And the oil oxidation reading is high. I blame EGR for this, and for the soot. Perhaps I need to do the next oil change at 16k miles to keep the soot at about 2.0, and avoid some of the oxidative thickening? TBN looks fine at 18k miles. On the last oil change, it was completely depleted at 20k miles. A new thing to worry about is the increase of Sodium and Potassium. Sodium went from 11 to 17, despite the shorter OCI. And Potassium increased from 3 to 5. Maybe the EGR cooler is beginning to leak coolant into the intake? EGR is nasty.