It depends on if you have used this oil for a long time in this engine and you got more miles out of the oil before adding or this is a new truck to you and you are doing a base line type of question. But yes a liter in 5000k could be considered normal. It becomes abnormal when you loose a litr in 1000k miles. So you may want to include more information about where you are and if this truck is new to you, how many miles on the engine, ETC. with more information you better informed information from the people you are asking this from. later robbie