Olszak was formerly part of the German Empire. In the German Empire, the place was called Pilzmühle.
The place is now called Olszak and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Pilzmühle | German Empire | Brieg | 1939 |
| Olszak | Under Polish administration | Brzeg m. | 1945 |
| Olszak | Poland | Opole | 1992 |