Recent events have compelled me to contemplate the Oxford comma to an even greater extent than usual, so let me share a story to convince you that, in addition to using the Oxford comma in writing, you should enunciate it in your speech.
I was getting pizza some time ago. But I must note that it was one of those pizza places where they make little quadrilateral pizzas for a single person ("single" having two meanings, probably). I normally wouldn't concede to the expenses associated with such a bourgeois establishment, but the meal is quite cheap when one orders a full-sized square pizza―probably because they aren't meant to be eaten in one sitting―and, most notably, the meal comes with a free side order.
As such, the cashier asked which side I would like, and I will transcribe this in such a manner as to accurately represent her enunciation: "You want bread chips or carrots?"
I cannot think of how to tell this anecdote without now giving away the catch, which the keenest among you may have already ascertained: The sentence was actually, "You want bread, chips, or carrots?"
But I am not the keenest among us, and the fact that there was no pause between the "chips" and "or" suggested, in my mind rightfully accustomed to the Oxford comma, that there were only two items: bread chips and carrots. I sought to confirm this, asking, "Bread chips?"
And she, wielding the apathy of an employee who unwittingly tempts the manager into automating all the cashiers, recited the items with the selfsame cadence or lack thereof―"Bread chips or carrots?"
This corroborated my confusion, and I thought to myself, I have no idea what bread chips are, but I know I don't want carrots. So I said, "BREAD CHIPS."
She replied, "Chips?" And then I might have said "BREAD CHIPS" again―I forget―but apparently I conceded to chips eventually, and went to await the production of my comestibles thereafter. Not even at this point had I come to realize the situation, as my friend labored for some time to explain it to me.
The Oxford comma was not the instigator in this story; it was a reluctant spectator, a single tear running down its cheek. I implore you to take this experience to heart.