ॐ नमों शिवाय् ...

Got a mail from Patanjali Ayurved and I was Really Amaze to see usage of "OM" Instead of Hi - I Do not know why but i really felt very great by reading OM

I read somewhere as well that there are many benefits of Chanting OM
Should we think to Use OM whenever possible in my daily life instead of Hi?

What do You think ?