Erasmus writes (I apologize for quoting Erasmus as often as a Fundamentalist quotes the Bible, but at my opinion, he is the safest author on the matter):
"In practice, we get our best results with a w3:w6 ratio of 2:1. This ratio can be obtained by adding w6-rich sunflower and sesame oils to flax oil. The 2:1 ratio and the above oils are used to make Udo's Choice Blend."
(Fats that heal, fats that kill, p.291)
Of course he doesn't give his complete secret. But from information everybody can find in "Fats that Heal, Fats that Kill" (p.237) I tried to infere the ratio of flaxseed oil, sesame oil and sunflower oil he uses in his blend. I found that the percentage of each oil is about the following: to make any quantity of balanced omega3-omega6 oil blend, just mix 84% flaxseed oil, 8% sesame oil and 8% sunflower oil. (If Erasmus reads my message, he will no doubt laught at me).
Bur recently, Erasmus changed a bit his recipe and added to flax seed oil+sesame oil+sunflower oil some Evening Primerose seed oil, rice oil and oat germ oil. He says that these additions are ‘minor’ ingredients with major health benefits.
I just woul like to underline that the ratio 2:1 is for healthy people. People with cancer, for exemple, should take flaxseed oil only which contains very few omega6.