This is how I sold lubes. We had minimum amounts for delivery. This could be waived for good customers who regularly bought above the minimum. You want to keep their business for the long term, so if you lose a little on a sale once in a while, it can be considered a normal cost. On the other hand, customers who always bought at the minimum (or paid slowly, or who always had a special problem) didn't get the waiver.Unless you're spending a few hundred every month, I wouldn't expect special treatment.