Castrol® GTX® 10W-40 is a premium conventional motor oil that has been helping to extend engine life for over 50 years. It is specially engineered to prevent harmful build-up of sludge while protecting against new oil splatter formation better than tough industry standards.
Sludge is a thick, tar like substance caused by severe driving conditions such as heavy traffic, poor fuel quality, harsh driving conditions and exceeding oil change intervals. Sludge can block your engine's vital oilways like cholesterol and if untreated, can rob an engine of its power and ultimately its life.