Use the serial/Oxford comma because the Maine courts say you should:
If you have ever doubted the importance of the humble Oxford comma, let this supremely persnickety Maine labor dispute set you straight.
. . . .
This is what the law says about activities that do NOT merit overtime pay. Pay attention to the first sentence:
The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of:
(1) Agricultural produce;
(2) Meat and fish products; and
(3) Perishable foods.
Of course, the Oxford comma gets all the credit, but note the parallel construction also makes it clear which verbs apply: Canning, processing, preserving, freezing, drying, marketing, storing, packing are gerunds. Shipment and distribution are not. If they were to be included as equivalent, they would be shipping and distributing.
So take the advice of your humble Director: Use the serial comma and parallel construction–verbs ending in -ing, infinitives, gerunds (which are verbs ending in -ing that act as nouns as in the above example), and so on–to clearly express items that are the same in the purpose of the sentence.
Writing and to express oneself clearly are incorrect and confusing.