My aunt runs/owns a gas station in the Okanagan. It's a Petro Canada and from what I understand, it's on the owner/operator of the station for maintenance and the like. Apparently P.C. is the nameplate, supplies the fuel and store items but not much else. She's not extremely wealthy from this venture and I remember years ago her talking about having to shell out hundreds because some buffoon broke the sink somehow. I'd have to assume the same goes for compressor parts, although she doesn't charge for air at this point.
Bang on, MC Fatigue. I worked at Petro-Can on 4th and Cypress in Vancouver for 6 years. The person with the name on the station is the one who pays for everything. The owner of our station even paid for the gas on delivery. You have to sell big volumes of fuel and huge amounts of C-Store sales to make any money. We had a tunnel car wash, too, which was super expensive to run.