Copper Turbo Oil Feed Restrictor AN4 Fitting, M12 x1.0 Thread Copper Turbo Oil Feed Restrictor Fitting for many Turbos, GT35, T25, T28, T3, T4, T6 AN4 Fitting Size to Oil Line M12 x1.0 Thread to Turbo Note: Different turbo has different oil inlet thread. This ONLY Fits M12 x1.0 Thread. Oil Fitting has built in Restrictor to supply proper oil pressure for the turbo which is critical for normal Turbo operation. without correct restrictor, Turbo oil seal might be blown and leaking oil.