KC OIL SEAL | What KC OIL SEAL ? NOK OIL SEAL | A2Z SEALS Specification Table KC type Nitrile Rubber (NBR) Lip Material NOK A727 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.