well, I think I can asnwer that for you since I work at a dealership. normally we'd say 4 qt if we use less than 4.5 qts. So, basically any amount of under x.5 then it is billed out as x. Otherwise if the amount of oil being used is over x.5, we bill it out as the next number. In your case, the dealership probably used less than 4.5 quarts.