the oil is not a barrier to keep air in only the seal does so. max amount of atf to use is 3 oz per shock not six. normally 2 oz per instructions are used, using 3 oz provides a firmer ride and a little more capacity. you can fill it up via the air hose fitting connection on the shock no need to take it apart.
if they bled down like u stated than the air seal is leaking or if not and bouncing then the sealed lower section of the shock has failed. there are replacements avail.