Hello! I am а proud owner of an Audi a6 c7 3.0bitdi. The car suddenly started losing antifreeze at 500 ml per 1000 km. The heating of car works perfectly, it doesn't overheat, the engine is dry. With more aggressive driving, it loses more antifreeze. Also, after about 500 km of driving, the first 5-10 minutes it smokes thick, white smoke. Can you give me some advice?