At our grocery stores you can buy a gallon of food grade white vinegar. Works great. I think it undoes old fabric softener on towels so they absorb better. But I have no empirical proof. No vinegar smells after it dries. I can smell it while it washes in the washer.

Just standard white vinegar sold in regular grocery stores. I use cheap food grade vinegar.

I just use food grade stuff for myself. Mostly because I can only get the cleaning vinegar in large jugs where I am. It works perfectly.

I think balsamic vinegar works best.