Castrol GTX Ultraclean is a synthetic blend engine oil available in 5W-30 and 5W-20 grades. The double-action formula has been proven to clean away the sludge that can block engine oilways and helps prevent new sludge formation thanks to its synthetic technology. Provides advanced protection against viscosity and thermal breakdown. The premium-quality base oils and anti-wear additives help extend the life of your engine. This motor oil gives superior protection against high-temperature deposits.