Pep Boys has a $10 off coupon for a conventional oil change (up to 5 quarts). Should bring the price down to $14.99, plus tax, plus waste disposal fee, plus processing, plus shop fees, plus etc, plus and so on.
But even though you're coming out the other end at probably somewhere slightly north of $20, it's still better than you could do.
Here's a link to the coupon (which is also attached): https://static.pepboys.com/docs/p...Final1.pdf
And here's a link to make an appointment: https://www.pepboys.com/eserve/appointment