I had the local Hyundai dealer idiots done exactly the same on mine on its 12 months first service. Almost 1 liter of oil more. I sucked it out through dipstick tube with oil sampling hose/kit than went back to the dealer and had the oil drained out (I supplied my own oil initially and the helpful idiots advised me that they needed to top up as I didn't supplied them with enough quantity (5.0 L) which made me suspicious.
The manual says that 5.3L of oil is the REFIL CAPACITY for the DIESEL i30. When I did the First oil change (7,500Km) myself I only drained around 4.3L of oil from the engine. This is because it is almost impossible to drain the WHOLE amount of oil as there will always be some left on the oil pan (Unless you are using a vacuum pump and even then.....)
So if you drain out around 4L and you go add 5.3L then you see why it does not add up. My car took around 4.5L of oil and it was still just below FULL. (around 500ml remains in the oil filter container and oil filter alone).
A 5L oil container should be MORE THAN ENOUGH FOR ANY SERVICE CENTRE for an oil change. Them telling that a 5L oil supplied was not enough is just pure bollocks and they are trying to make money.
There is a warning on the manual "DO NOT OVERFILL". It is not good for the engine, similar as when there is NOT enough oil.
