Billet Aluminium Oil Filter Housing Cap for BMW / MINI B46 / B48 / N47 / N57RTMG Performance introduces a solution to a critical engine component. Manufacturers often use cost effective materials like ABS plastic, which over time degrades and deforms under high temperatures and pressures. The oil filter cap is one such example. Our company has designed a BILLET aluminum oil filter cap, resistant to polymerization and deformation under extreme conditions, preventing oil leaks and failures, particularly in racing applications.