I had my car serviced at the Volvo Dealer. 2012 S60 T5. Oil level on dipstick shows over full. I brought my own oil to dealer (full synthetic 5W30 Mobil 1). Dealer said "bring 7 quarts as capacity is 6.1 quarts and we will give you back the remainder". Did not get remainder back, and when I checked dipstick after getting home, shows overfull. I suspect all 7 quarts were put in engine. Is this dangerous? If so, should I bring car back to dealer to have them drain off some? Expert answer is?