2007.5 Dodge Ram 2500 Cummins 6.7 V8 I did two close UOAs to investigate the potassium situation. Turns out it is a result of crankcase vent filter failure. Oil has been getting into the charge air system which leaches potassium from the intercooler. Coolant passed an exhaust test and system holds either vacuum or pressure overnight without any movement. Silicon is up because it is an additive in Redline. First run was Amsoil AME 15W-40 (diesel and marine 12TBN, a CI4+ oil), second was Schaeffer 15W-40, third is Schaeffer 5W-40, and last is the Redline 15W-40. Why so many oils? Trying to see if something will give me less iron. Nope. This engine in these conditions is going to drop 2PPM per 1K miles no matter what. Schaeffer 5W-40 did not hold TBN as well as 15W-40 did, and I have no idea why soot levels have all of a sudden plummeted. Maybe the first run of Schaeffer oil just scrubbed the engine clean of soot. Or the bypass-in-filter LF9028 I use has done some serious cleaning. Dunno, but I like that alot. I didn't change the oil filter or add any makeup oil at all. Fuel remains a non-issue on my deleted truck. Speaking of being deleted, I think I'm just done with CJ-4 oil. I'm going back to Amsoil AME or that 15TBN TR oil. My engine is happy enough with 25K mile oil changes that I just want some fat viscosity and some fat TBN. Set it and forget it. I don't need CJ-4 or CK-4 oil to protect anything. Cummins actually advises to "Do not use" oils meeting either spec in engines without EGR or DPF. So bye-bye. This engine now has 485,000 miles on it. I'd like to pass 1 million. Factory leather has no tears, dash and all other plastics have no cracks, and the body is as sexy as ever. Not bad for 13 years old.