Castrol GTX High Mileage 20W-50 and Mobil 1 45000 5W-30 High Mileage Motor Oil are engine oils that are highly rated by Bestcovery, as of 2015. Other engine oils recommended by Bestcovery include Pennzoil High Mileage Vehicle Oil and Amsoil Extended Life Synthetic Motor Oil.
Castrol GTX oil is formulated with a specific blend of additives for high mileage vehicles. These additives help protect the engine from wear that happens over time. Mobil 1's synthetic high mileage engine oil also features a special blend of additives for extra engine protection. The additives assist with issues such as sludge build up and small leaks.