1986 Toyota pickup, 301,000 miles, Castrol 20W-50 to 20,000, Castrol 5W-50 to 40,000, Mobil 1 15W-50 since 40,000, Toyota then Wix filters, 3000-3500 OCI.
1999 Chevrolet Cavalier, 212,800 miles, Mobil 1 15W-50, Wix filter since day brought home from dealer, 3000-3500 OCI.
Both vehicles in daily use.