Does the Oral Law Exist?

So I'm watching this show called the Naked Archeologist. In one episode, he tries to figure out what fish was used for a particular dye. After some searching on Google I found the link above. (stay with me...)

Believe it or not, the custom of the Tallit stripes are an outgrowth of the Torah command to attach one blue thread to the Tzitzit, and also used for dying priestly garments. (see Exodus 25:4 and Numbers 15:38)

The "Techelet" was a bluish color, obtained from the fluid of a sea creature called the "Chilazon." (Tosefta Menachot 9:6) It is found on the coast of Northern Israel, though here is a disagreement among scholars regarding what the "chilazon" actually is. Some say that it is a snail, while others say it is a squid. There are some who claim that the "chilazon" is actually a mollusk.

Correct me if I'm wrong. There was a particular dye that was used for dying priestly garments. We no longer know what that dye was made of.

If the oral law contained that information, it is gone. That's why we rely on Scripture alone.