Oil loss Facer Bj200, 2.2litres 16 V, 144 hp

Hello to each other. I have the following problem, was at the beginning of the week to make oil change, (5W40) with oil filter of course. The car should be looked through as I want to drive next week dammit on the holiday! It seems to be all right, they told me! Today I looked in the engine room and saw on the right back side that there is probably something leaking (it has run out a bit(lubricated, not much)(probably oil !?) I describe it a little as I don’t know how to get there. So I have a facelifter BJ 2000, 2.2L 16V, 144 HP. If you are standing in front of the car and the hood is on then on the left side of me is the air filter box! So where the filler nozzle for the oil is there right of (behind) there goes from the engine housing a thinner hose down where after a few centimeters of the hose is attached to such a steel tube, this is then at the lower engine block or clutch proximity? with 2 screws screwed on. This area is a little wet, think it’s oil. (if I got it with the flashlight and I could see it seems to be greasy on the side too.But can I not say/see directly. (Can it be from a defective lid seal?) What can that be? How bad is that? Do I have to do it before the holiday? Wouldn’t it have to be seen at the holiday check? Need your advice! I thank you for the answers! mfg Omega73