Steve Ray has a list of 35 loaded Questions for "Bible Christians" (quotation marks his)(link to the whole list). This is number 5/35. I'm trying to provide the answers in a common format, for easy reference.
5) Some Protestants claim that St. Paul condemned all oral tradition (Col 2:8). If so, why does he tell the Thessalonians to “stand firm and hold to the traditions which you were taught, whether by word of mouth or by letter” (2 Thes 2:15) and praises the Corinthians because they “hold firmly to the traditions” (1 Cor 11:2)?
We don't necessarily condemn oral tradition.
1) "Oral tradition" can refer to various things. There's a sense in which the minister preaching the gospel is tradition-ing (passing on) the word of God in an oral form. This in itself is not a problem, but it should never be given an authority equal or greater to the Word of God itself.
2) The danger of human traditions corrupting theology remained an issue about which Paul was concerned:
Colossians 2:8 Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.
3) Given the dangers of human tradition, the best way to distinguish between human traditions and the Word of God is by comparing a church's teaching to the Bible.