Since we are talking about Oil (& filter) changes I'll mention what was the norm in the USA when I was there on company business for extended periods (1997-98) - There the Tyre 'shops' also did Oil & Filter changes for a reasonable sum - depending on the amount of Oil used the cost was between $40 to $60 parts and labour. There wasn't a need for the O&F change to be done by a dealership. Oil & Filter changes appeared to be every 5000 miles no matter what make; from what I saw every car's service book had separate pages for Lubricant service and other parts of the service.