Have a 2014 JGC Diesel, did lot of research looked at 100 or so oil samples from VW,MB,BMW etc using low SAPS oil, the common denominator was high wear, Fe, Al etc. sometimes above 100ppm in regular OCI. I'm seeing more concern for keeping the DPF from become plastered with antiwear metals to downgrade its performance rather than have concern for the engine itself.
After the time suck of research i'm running Rotella T5 10W30. May switch over to T6 or M1 TDT in summer. 10W30 has less vi improvers, good soot control, and anti wear.
FWIW, i'm getting 27mpg 50/50 mix city highway.