I used Castrol Magnatec 5W30 on my crown vics last OCI and LOVE IT !!! 3K miles/2 months later and oil still looks CRYSTAL CLEAR !!!
Got it at local walmart for around $16.50. They priced match online price
05 Silverado Z71 5.3 DELO 400 XLE 10W30/FUG XG3675
01 Suburban 5.3 Mobil 1 HM 10W40/M1-206A
1982 TRANS AM (KITT) Mobil Super 5K HM 10W40/M1-302A