Summer months I have the dealer put in the "M" oil which I believe is 10W-60. I use Castrol Edge 5W-50 for supplemental adds - about one quart every 1400 miles.

Winter months I go with the 5W-30 on the dealer oil change and use Castrol Edge 10W-40 for the supplemental adds. Those tend to come every 1000 miles with the thinner base.

I change every 7500 to 8000 miles.

2002 X5 3.0 351,600 miles
2014 428i 44,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under restoration