ok, fine... those two are synthetic and semi-synthetic.
My case. On first service (month ago) on 10000km, they put in new MINERAL oil. Whole service price was 4500din (~55e) ... few days ago, my friend with same car, paid same service 6500din (~80e) ... they said it was because difference in price of oils! ... he maybe get (god knows which) synthetic oil...
of course, same authorized service (reno sekulic, vetrnik)
...and ideas of what should I do?
...maybe to do next service few thousands km earlier, find recommended oil and bring it with me to service?