EDIT: This question is not addressed by Oxford Comma Conventions, if I'm wrong, then please provide a link to a particular answer or comment that does address my question. (Such links appear in timestamps.)
In Writing: Grammar, Usage, and Style, Jean Eggenschwiler & Emily Dotson Biggs advocate a serial comma in the following sentence:
He bought a dishwasher, microwave, refrigerator, and washer from the outlet.
Yet, the inclusion of a serial comma seems to introduce an ambiguity: It seems unclear whether all items (i.e., the dishwasher, microwave, refrigerator, and washer) were bought from the outlet, or just the washer. Would omitting the serial comma be better? I.e., does sentence
He bought a dishwasher, microwave, refrigerator and washer from the outlet.
improve upon the original?