I worked at a Mr. Lube when I was in college. A few notes.
- You will be charged extra for bottled oil instead of bulk oil, but you get to pick your brand, type and weight. Bulk oil is usually a major brand (we used Castrol), conventional, and almost universally 10W-30.
- You will likely not be allowed to "bring your own" and pay labor. A) They charge more for their own stuff - imagine going to a steakhouse and asking them to grill your porterhouse from home for the cost of labor. B) They will tell you it's for liability purposes, so that if there is a defect in the oil they put in that you brought, you could try to sue them. Sounds strange but I can believe it could happen.
- They will use their own brand of filter unless you pay extra for an OEM filter.
- Make sure you ask for the grease fittings to be done. They're supposed to anyway, but they're encouraged to "forget" when it's busy.
- They will try to sell you an engine flush every time. You only need one if you've abused your oil. Before you go in, check your oil, if it's midnight black, you should get a flush, but if it's only brown, decline.