Answer:
Fuels backyard get-togethers
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
What stays the same size no matter how much they weight?
Many have heard it, but nobody has ever seen it. It will not speak until spoken to. What is it?
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?