Most engines are equipped with disposable and non removable paper gasoline filters. The replacement cycle of in line diesel fuel filter is generally 10000km. If you add less gasoline impurities, 15000-20000 km replacement is not a problem. The filter is marked with an arrow at the inlet and outlet. Do not install it reversely when replacing it.
Fuel filter paper
Cross Reference For WK6001
Alco SP-1397, Blueprint
ADL ADV182309, Bosch F026402066, N2066, Champion CFF100499, L499/606, Coopers Fiaam FP5929, Filtron PP993, Fram P10820, Hengst H332WK, Mecafilter ELG5426, Magneti Marelli 71760474, Mahle KL658, Mann 1075506S01, WK 6001 Motaquip LVFF697, Purflux FCS776, Tecnocar RN328, UFI31.921.00, Sofima S1921B, Volkswagen 4F0127401F, Wix WF8432 SAKURA FS-31980