Castrol Magnatec 5W-40 A3/B4 4L Engine Oil

Drivers of high-performance petrol and diesel vehicles rely on Castrol Magnatec 5W-40 A3/B4 to keep their engines protected from the moment they turn the key. The 4-litre bottle is a practical size for regular servicing, whether you're topping up between changes or doing a full oil replacement in a home garage. Its synthetic technology formulation is engineered for modern engines that demand robust protection under high loads and varied temperatures.

Key specifications

• Viscosity grade: SAE 5W-40
• Volume: 4 litres
• ACEA specifications: A3/B4
• API specifications: SN/CF
• Manufacturer approvals: MB-Approval 229.3, VW 502 00 / 505 00, Renault RN0700 / RN0710, Fiat 9.55535-M2
• Kinematic viscosity @ 40°C: ~80 cSt
• Kinematic viscosity @ 100°C: ~13.5 cSt
• Density @ 15°C: ~0.85 g/ml
• Pour point: ~-39°C
• Flash point: ~205°C
• Sulphated ash: ~1.2%
• Total Base Number (TBN): ~10 mg KOH/g
• Container material: HDPE plastic

Why choose it

Castrol Magnatec's Intelligent Molecules cling to critical engine parts, forming a protective layer that reduces wear from the first start. This 5W-40 grade flows quickly at low temperatures for easier cold starts, while maintaining a stable film at high temperatures. The A3/B4 rating means it meets stringent requirements for extended drain intervals and high-performance engines, making it a dependable choice for both petrol and diesel applications.

Ideal use cases

• Regular oil changes for vehicles requiring ACEA A3/B4 5W-40
• Topping up between service intervals
• Engines with manufacturer approvals listed above
• Drivers seeking extra protection for stop-start city driving or high-speed motorway use

Good to know

Always consult your vehicle's handbook to confirm the correct oil specification. Store in a cool, dry place and dispose of used oil responsibly at a recycling centre. The 4-litre HDPE bottle is easy to handle and pour, with clear labelling for quick identification.