I have 2017 A4. Recently took her to a garage for an oil change. They added oil before it was drained by mistake. They said they did not start the car. How would they know there was too much oil? There is no dipstick. After they drained it completely and put the required amount of oil in, we started the car and it smoked a great deal. I drove at home, about 15 km, and every time I stepped on the accelerator great bellows of smoke. Come out the back. What would cause that and how to check the engine to ensure everything is OK now. The smoking stopped after the car sat for about four hours. The garage said they will correct whatever is wrong.