How do I know whose oral traditions are correct?
The Orthodox are just like the Protestants,and Moslem, divided, and basically agree to not disagree, so as to present themselves as a unified body.
That said, if you were to argue that a certain group of Orthodox are united worldwide and are the Apostolic Universal Church, well then, you have only two choices as to what Church follows apostolic oral tradition and correctly interprets scipture correctly, is the final authority on scripture "(2 Peter 3:16) "As also in all his epistles, speaking in them of these things; in which are certain things hard to be understood, which the unlearned and unstable wrest, as they do also the other scriptures, to their own destruction.(2 Peter 3:16).
The two choices are The Catholic Church or one of the Orthodox branches.
One would be better off with either choice, than with their own one man religion, being one man infallible authority of himself, as are the Protestant "bible only" interpreters (all of Protestantism).
As to which to pick Catholic or Orthodox that's your job to figure out. At least I've eliminated all the chaff for you. It's down to two.
Easy - you judge them by the Bible. Both fail the test, however.