I meant that he entirely transforms completely into the kyuubi, not that it would run out.
I was confused by the fact you said; "to leak out at that certain point, and if he goes further the entire chakra would excape"
But to you post above then yeap hardcore you can see it at 4 tails... But The stronger naruto becomes the more tails he would need to grow to go Kyuubi or Mini Kyuubi... maybe in sage mode Naruto could stop the transformation at 4tails...
By The time Naruto is Hokage... The full 9 tails should be out and he wont transform...
My Logic is 1/4 Spiritual energy + 1/4 Narouts Chakar + 1/2 Nature Chakar would turn Naruto into a frog... because it is unbalanced...
Same thing with the 9 tails chakar because he had more 9tails chakar then his own to balance it out he turns into the 9tails Mini kyuubi... Soo if he was able to match his chakar with the 9 tails he would be sweet...
Younger Naruto chakar was even with the 9 tails when fighting Haku... then he learned Rasegan and summoning which made him stronger which meant more Chakar... so when fighting Sasuke at the Vally if the end... He grew the first tail and did not tranform...
Well thats my logic...
The stronger Naruto become the more tails will come out but becasue it balances his chakar he wont transform!