I work at a dealership. The price WM sells oil for, is what we pay for it from a distributor. Hard to compete with that. People complain and moan about paying $32 for an oil change, and expect the moon and stars in return when they do have it.
Let's look at the average oil change. We charge no labor, just markup on oil and filter. Non-bulk oil (Pennz, etc...) sells for lets say, $5 per quart. That's $25. Filter, $8. We make $1 per quart on oil, and about $3 on a filter. That's $8 "profit".
That does not cover the lube tech's wage, $10 per hour. The wash tech probably get's $10 per hour. We are already in the hole. Now, there is the expense of chemicals and waxes to wash and clean the vehicle, not to mention the water bill. Then, most customers want a loaner to go to town so they don't have to wait. At two gallons of gas burned, there is easily another $6 in gas expense. Or, you have the customer that wants you to pick their car off then drop it off after it is done. They takes tech time and money in wages.
As you can see, oil changes are not profitable for a dealership. Paricularly when they try to stay competitive with WM oil prices.