ZF OIL SEAL | What ZF OIL SEAL ? NOK OIL SEAL | A2Z SEALS Specification Table ZF type Nitrile Rubber (NBR) Lip Material NOK A103 NOK OIL SEAL Nok oil seal is a mechanical component used to seal oil. It isolates the parts of the transmission component that need to be lubricated from the output components so that lubrication and leakage are not allowed.