The term "old oil bar" is a colloquialism used to refer to those who are experienced, sophisticated, smooth and worldly. These people usually have the following characteristics:

Rich experience: they have a lot of experience in society or a certain field, so they can cope with all kinds of complicated situations and interpersonal relationships.

Smoothness: they are very smooth in dealing with things, able to deal with all kinds of complicated problems and conflicts properly, and not easily offended.

Oil-smooth and cunning: They may sometimes appear cunning and dishonest, and are good at using words to hide the truth or shirk their responsibilities.

Elusive: They have a deep mind and are not easy to be caught, and sometimes they may even give people a feeling of inscrutability and unpredictability.