Unless you have a long term, and or personal reputation with a shop, expect nothing for free.
Nothing.
Do you bring the techs or service writers movie tickets or a bottle of whiskey at christmas?
Everything cost money, and unless you have a long standing relationship with a shop, nothing will be free, nor should it be.
Now, if you are known as a long time customer, easy to deal with, throws a bone the service guys way once in a while, then it becomes a different story. They will make an effort to take care of you, because you make the effort to take care of them.
If you are relatively unknown, or known but difficult to deal with and demanding, you will get no breaks, and be charged for everything.
My dad is a 25 year flat rate mechanic, that now runs one of the highest grossing dealership shops in calgary. We discuss this topic all the time.
The above statements are from him, to me. Shops are no different then a restaurant or local pub. Its all about establishing the relationship.
Not being negative. Just pointing out that you more then likely have nothing to be angry about.
Lastly, of course the oil is marked up. How do you think they make any money on oil changes. Even with mark up, there is no money in oil changes, and they certainly arent going to it for free, or at a cost to the shop.