How about answering the first part of the question?
I notice that every time the question is asked of what those teachings are, NOBODY ever answers it.
As far as the claim that God promised to keep the oral teaching from corruption, that is not what those verses say.
John 14:25-2625 “These things I have spoken to you while I am still with you. 26 But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you.
That verse can only apply to those disciples to whom Jesus was directly speaking as nobody else heard the words that He said to them. John 16:13 is no promise of protecting oral tradition from corruption either.
There is no way to protect oral tradition from corruption and the attempt to claim it by the Catholic church falls flat because it is not even consisten4t with itself throughout its own history, much less with Scripture.
trebb asked some very relevant and interesting questions. To refresh your memory.....I guess a better question would be, "What does the Bible lack that would keep an interested person from reading, understanding, and appreciating the Good News of the Gospels. What does it lack to keep a person from making the decision to accept Christ as the Savior?"
So just where is Scripture lacking and why and why would anyone even think so?
Paul illustrated what tradition is: "For I delivered to you as of first importance what I also received, that Christ died for our sins in accordance with the scriptures. . . . Whether then it was I or they, so we preach and so you believed" (1 Cor. 15:3,11). The apostle praised those who followed Tradition: "I commend you because you remember me in everything and maintain the traditions even as I have delivered them to you" (1 Cor. 11:2).
The first Christians "devoted themselves to the apostles’ teaching" (Acts 2:42) long before there was a New Testament. From the very beginning, the fullness of Christian teaching was found in the Church as the living embodiment of Christ, not in a book. The teaching Church, with its oral, apostolic tradition, was authoritative. Paul himself gives a quotation from Jesus that was handed down orally to him: "It is more blessed to give than to receive" (Acts 20:35).
This saying is not recorded in the Gospels and must have been passed on to Paul. Indeed, even the Gospels themselves are oral tradition which has been written down (Luke 1:1–4). What’s more, Paul does not quote Jesus only. He also quotes from early Christian hymns, as in Ephesians 5:14. These and other things have been given to Christians "through the Lord Jesus" (1 Thess. 4:2).
So just where is Scripture lacking and why and why would anyone even think so?
This has become a circular argument. There were many gospels, books and letters in circulation in the first centuries. How do you know for certain that the ones accepted are truly "inspired"? Who made that decision? Moreover, by what authority did they make it?
Jesus never commanded his Apostles to write down anything. Instead, Jesus founded a Church and gave the Apostles the authority to go and make disciples and to lead the Church, and that is what they did – they went forth and ordained new bishops in various parts of the world, and trained the people on the Faith. It was at least 40 years until anything was written down – for 40 years the Church flourished and grew without any NT book at all. And when such books and letters were written and sent, they were to address specific problems in specific regions (like the Judiazers in Galatia, for example). These were helpful instruments created by the Church, for the Church. But the Church came first.