Is it polite for a son-in-law to call his father-in-law in front of outsiders?

Impolite.

Respecting the elderly and loving the young is a traditional virtue of the Chinese nation. If a son-in-law calls his father-in-law "father-in-law" when meeting, it is rude and immoral behavior. No matter what the father-in-law did before marriage to make you unhappy, What words were said that shouldn't have been said? Now that we are a family, we should put aside past grudges and respect the elderly.

It is important to address people by specific names and not by random names. As soon as a person can speak, his parents will teach him to call him mom and dad. Later, they will also teach him to call the relatives and people around him. Such people will be laughed at and blamed for shouting by mistake.