I got a 2003 certified used car. I soon need to change oil /brake fluid /spark plugs.
Do I need to go to an audi dealer? My friend who has an A6 suggests I can do these things at a regular mechanic and that I can change oil more often than 10k with the same budget. Also I can do these repair on weekends if I go to a regular mechanic. I have 2 yr certified waranty, and it may get invalid if service is not done at audi dealer. Any suggestions?

03 allroad 2.7T, 30k miles.