Castrol EDGE 0W-30 Fully Synthetic engine oil is suitable for use in automobile gasoline and diesel engines where the manufacturer recommends an ACEA C3, API SN or earlier specification. Advances in engine technology have led to increased power and efficiency, meaning engines work harder and under higher pressures than ever before. The only thing keeping metal engine components apart is the oil, so it needs to be strong and remain strong. Castrol EDGE Fully Synthetic is our strongest and most advanced range of engine oils. Its TITANIUM FST™ doubles its film strength, preventing oil film breakdown and reducing friction. Castrol EDGE with TITANIUM FST™: helping your engine perform at its best.