does it keep gasses from escaping?

 

Why do you want people to guess what the hell you are talking about?

Do you really think that everyone known what you mean when you talk about a "beer bottle capacitor"?

If it is a capacitor that uses water as it's dielectric, then it would not be unreasonable to put some oil on top to prevent the water from evaporating.

 

Similar to a Leydan jar. My guess the "oil" is the dielectric.

 

Or maybe an insulator? He mumbles something about oil on top here.

 

10w30 its to keep the water from evaporating

 

Any oil will work just a motor oil would be best. Cooking oil can mold its just to close the bottle off and keep the water in it.

 

I'd say its as good as any.

 

Yes keeps the gases from escaping! Oil is impervious to gases! I thought everyone knew that. Does the bottle still have beer in it?