Castrol GTX Ultraclean is one of the worlds most trusted engine oils. The modern world creates difficult challenges for engines. Poor fuel quality, heat and tough driving conditions can all lead to sludge that potentially shortens engine life. Sludge is a sticky deposit that builds up in an engines vital oil-ways and it can prevent oil from protecting the engine. Castrol GTX Ultracleans synthetic technology has superior performance. Its Double Action formula cleans away old sludge, and protects against new sludge formation, giving you more control over todays challenging conditions. Help extend the life of your engine with Castrol GTX Ultraclean.