- Feb 3, 2011
- Golden Meadow, LA
same 4.8 Vortec I've posted about before, now at 150k miles on the clock. It now does longer trips daily, 50 miles one way to work and 50 miles home. My friend was inquiring about extending his oci, how does either M1 HM 10W30 or Castrol 0W40 for a 7k oci sound? I'd use either a tough guard or ultra filter. I was also considering QSUD 5W30 or 10W30, I've heard nothing but good about those two oils on here. Any reasons to worry about the 0W40 thinning out too much in 6-7k miles?