Dealer Service Recommendation Request

The adventure that is the summer road trip will soon commence. Consequently, by the middle of July I expect to be in Chicago (for the first time) where I wish to treat the Prius to a mid-trip oil change. Locally, the irrational apprehension exhibited by non-Toyota service personnel in the greater San Diego area when it comes to the Prius has led me to find a service department I can trust to follow my instructions: "underfill" with three quarts of oil which I supply. I'm hoping one of our fine Chicagoland PriusChat members will direct me to a dealer service department capable of accommodating my requests without objection and accomplishing the task with a minimum of hassle. My primary aim is to ensure this small chore not balloon into a nuisance when I am least equipped to deal with one. Any recommendations based on personal experience or community consensus are greatly appreciated!