I've guilty of using the words 'fixin to' instead of the words 'about to'. Several years ago I became very aware of this when my sister became engaged to a properly articulate man. So, I trained myself to say the proper words. For example, instead of saying "I'm fixin to go to the store", I properly said, "I'm about to go to the store". It took me a while to cut out a word I had used improperly for "30 some odd" years. BTW, would "some odd" also be a southernism?
I laughed at the little old lady "ism" because about a year ago, my husband cut off one of those little old Southern ladies with his big, extended cab, diesel Ford truck. He needed to get in her lane quickly. So, he sped up and changed lanes closer to her than he intended, therefore cutting her off. This dear, little old lady, who could barely see over the steering wheel, sped up, changed lanes, and as she passed my husband, lifted her little ol' arm up high and proceeded to flip him the bird with her little ol' middle finger. So, beware of sweet little ol' spunky Southern women.
As far as y'all goes, this southern lady has never used it as a singular personal pronoun. I only use it as a plural personal pronoun. So, I guess I'm ok, grammatically speaking that is.

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