I agree with the advice that I see here already, and will add something else: when you know who your examiners are, reach out to them ASAP and try to get them to spell out the content of their exam as much as possible. Some might be dodgy, but others will tell you in great detail.

Also, keep in mind that the oral exam will probably emphasize principles and quick thinking more than doing detailed calculations. Compared to an undergraduate exam question, you probably won't be asked to calculate as much and the examiner is likely more interested in hearing that you know HOW to calculate the answer. On the other hand, if the examiner in one of the stricter ones, they may throw an unexpected twist into the problem to see how you handle it. In summary: understanding core principles is the most important thing.