Changes

Take free Tesco bus from main Bus station (Dworzec PKS) to shopping center Bielany. Get off at the last stop, go right along the Tesco (way back) to Czekoladowa street, then turn left (along the tesco), then cross the street, turn left, go under the bridge (highway), turn right and go along the highway across the field, you'll get to the petrol station (you have seen it from the bus). Where you can ask people for a hike or try to hitch someone going out from Wrocław by an exit road next to the station (the same situation as going towards Kraków, you're just on the other side of the highway). You can also take the free Auchan bus from the Dworzec PKS. Get off at the last stop and you will see a gas station from there. Just go directly towards it without crossing any streets (only these belonging to Auchan's car park) and you will be in the same place as in the Tesco bus option. Good luck!