It was time for an oil change on my 4.3, 5 speed work truck so, on the advice of this board, I went with the Castrol 0w/30 made in Germany "gold". The truck has 20,980 miles, most of them on M1 5w/30. The gold passed the family "freezer test" with flying colors (BMW high performance motor oil did not, M1 always does) so in it went. This board is correct in it's assumption that the GC is a somewhat thicker oil and I'll be ****ed if the engine doesn't sound quieter with the GC in it! I reset the OLM and will change out the GC at 5k and see how it looks and feels ( used M1 always feels smooth and velvety). If all goes well I'll probably stay with the GC mostly because of the quietness. Cheers all! double vanos