Hello,
I'm one of wireshark core developers, you can check my contribution here: [login to view URL];a=search;h=HEAD;s=Jakub+Zawadzki;st=author
Depending on the needs, I can create dissector and push it into wireshark repository (so you will no need to worry that it will stop working after API/ABI change), or make a plugin.
It seems that OBD-II have standard PIDs, and vendor PIDs, for which documentation might be not public, and would require buying documentation or reverse engineering.
I am not sure what's the scope of project - do you need only standard one, or you will provide documentation with vendor one also?
You mentioned Lua dissectors, lua is supported, still most of dissectors are written in C.
Is Lua preferred for you (like do you want to have possibility to modify analyser, without recompiling?).
Could you provide example capture file(s)?
With regards,
Jakub Zawadzki.