Castrol GTX is one of the most trusted lubricants by consumers in the world. It s more than just oil. It s liquid engineering. It is this technology that protects against problems, such as sludge formation, that your engine faces every day. Driving in adverse conditions such as stop-and-go traffic and short trips, adverse weather conditions and increased oil change intervals can cause a tarry material called sludge to build up in the engine. You can t see the sludge forming but it can impair your engine s performance and cause it to prematurely wear and tear. Protect your car from sludge formation with Castrol GTX.