All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
You must advise him as much as you can. The Prophet ordered the one who sees an evil to change it physically with his hand if he was able to do so. If he could not, he should change it by his tongue (by advising and/or condemning), and finally by (detesting it with) his heart, and he informed that this is the weakest level of faith. [Muslim]
You should advise him in a kind and wise way. Allaah Says (what means): {Invite to the way of your Lord [i.e. Allaah] with wisdom and good instruction.}[Quran 16:125]
Since he performs the basic pillars of Islam, it is hoped that his manners will eventually improve, Allaah Willing. However, if you fear that he might inflict unbearable harm upon you, then you are not obliged to advise him. The Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said that a Muslim should not humiliate himself. When he was asked how a Muslim could do that, he answered that he would do so by exposing himself to an unbearable affliction and hardship. [Ahmad and At-Tirmithi]
In all cases, you must detest his notorious behaviour in your heart. Remember that the Prophet, sallallaahu ‘alayhi wa sallam, said that the minimum someone should do to change evil, is to detest it with his heart as this is the weakest level of faith.
Allaah Knows best.