Because of aluminum material has low density, high intensity, and good plastic and corrosion resistance of the particularity of ability, according to the engine structure characteristics, some engine need to be installed to use aluminum material housing. Same theory as iron housing oil seal, according to the design of location holes of the installation metal housing, directly install the oil seal on the engine body with screw, very convenient to install and remove. International many OE manufacturers are using this new type of structure oil seals.