For a 2003 MINI Cooper S JCW (R53), BMW/MINI originally recommended:
Oil Type:
-
SAE 5W-30 or 5W-40
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Must meet BMW Longlife-01 spec (LL-01)
Oil Capacity (with filter):
-
Approx. 4.5 liters (4.8 US quarts)
A high-quality full synthetic oil like Castrol EDGE 5W-30 LL or Liqui Moly Synthoil is commonly used among MINI owners.