CASTROL GTX: Superior sludge protection to help extend engine life

Severe driving conditions such as heavy traffic, harsh weather conditions and exceeding motor oil change intervals can all cause the build-up of a thick, tar-like substance called engine sludge. If untreated, it can rob an engine of power and, ultimately, its life.

Castrol GTX is specially engineered to prevent the harmful build-up of sludge, reduce oil deposits and provide daily protection for your engine.

Keep your engine clean and help extend engine life by choosing the right oil from the Castrol GTX range for your next engine oil change.

Our new Castrol GTX ULTRACLEAN is the cleanest GTX ever. It helps extend engine life, giving you more control over today's challenging conditions.


Cars today have a tough life, and that’s not going to change as they get older – it may even get worse. Heavy loads, towing, extended motorway trips, and long periods of idling while waiting for the family – all these are tough driving conditions. 

They can lead to high engine temperatures, and to elevated levels of contaminants from burnt and unburnt fuel accumulating in the oil. These can all result in engine sludge, which can shorten the engine’s life.

Castrol GTX ULTRACLEAN’s synthetic technology has outstanding performance. Its Double Action formula cleans away old sludge, and protects against new sludge formation, giving you more control over today´s challenging conditions.

Help extend the life of your engine with Castrol GTX ULTRACLEAN.


  • Provides 50% superior sludge protection compared to tough industry standards*
  • Advanced protection against viscosity and thermal breakdown
  • Outstanding protection against high temperature deposits
  • Premium quality base oils and anti-wear additives that help extend engine life
*50% cleaner than the industry limit as measured in the API SN Seq. VG sludge test


  • SAE 10W-40
  • ACEA A3/B3, A3/B4
  • MB-Approval 229.1
  • VW 501 01/ 505 00
  • Meets Fiat 9.55535-D2/G2
What engine oil is right for my car?  Find out with our oil selector. We can also show you where to buy Castrol GTX Ultraclean.


Castrol GTX 15W-40 A3/B4 fights sludge, the engine cholesterol! 

Castrol GTX 15W-40 A3/B3 provides 25% better protection against sludge than the latest industry standard. Liquid Engineering protects against problems that your engine faces every day. 

Sludge build-up in your engine can lead to increased deposit formation, reduced oil flow and premature engine failure. 

Approvals & Specifications

  • ACEA A3/B3
  • MB-Approved 229.1
  • VW 505 00
What engine oil is right for my car?  Find out with our oil selector. We can also show you where to buy CASTROL GTX 15W-40.