I dropped my V off about a month ago at the dealer for an oil change and assumed they would just use the factory-recommended Mobile 1 synthetic. Well yesterday I decided to pop the hood and double-check the oil levels (I keep an extra quart of Mobile 1 in my trunk at all times) and the dealer had covered the "Mobile 1" cap with a Castrol Syntec sticker. Is this oil fine? Can I use the Mobile 1 to top-off the car? I'm kinda upset they used the Castrol but I guess it's really my fault for not asking.