This is for my dads 2003 Infiniti I35. 10,000 miles on M1 EP 5w30 and a M1 filter. Pretty much a 50/50 split between hwy and city. He bought the car with 66K
Was finally able to see the UOA. Definitely use a 40 weight. You shouldn`t have this much wear metal. 0W40,5W40,or 10W40. Nissan engines like thicker oils. And if your manual is like mine,3000/3 months. Don`t extend oci`s in this car.
Babbit type bearings contain lead and tin. If this lead is from bearings, where is the tin PPM? Even at that, the lead PPM are still within the acceptable range of 30 PPM. Nissan engines often show higher metal PPM than others, but as we know has nothing to do with actual engine wear and shorter engine life in Nissan engines. I would not use a 40WT oil in this engine that calls for a 30 wt oil.
Mobil 1 xw-30 oils seem to produce high lead wear in the VQ30 and older VQ35 engines. The chemistry simply isn't a good match.
As JAG suggested, M1 0w-40 (which is significantly different in more than one way) seems to work much better.
That said, the engine will most likely outlive the rest of the vehicle despite elevated wear from Mobil 1 use.
I must add that I own and drive a vehicle with a VQ30 but I am not an engine or lubricant professional.
I imagine that M1 EP is more suitable for extended service intervals than PP. (M1 0w-40 is also an extended service oil.) I was curious to see the condition of the oil in this UOA, but there wasn't a TBN to help with that. If you plan to do another UOA then I'd continue to use the same oil then switch to PP after the M1 is finished. While I suspect PP will do better for lead wear, everything else looks good in this UOA.
Was any top-up oil added?