I just bought me a zetor 6045 84mod .After an oil shift and 2-3ouhrs driving I chek the oil again-suddenli it was 19liters on the motor-it chud be 12liter. I think it is diesel in the oil!Where can it come from? it is not from the hydraulic steering,and its not water from the radiator!Can it come from diesel inj.punp or other places? engine has running 2200hour amd going fine,no black smoke!???