I think, if at all possible, a method of restricting what fluids can and cannot be placed into buckets would be useful for gating what fluids can and can't be moved early game.
While it's obvious lava would burn a wooden bucket, it's illogical to be able to move the fluid using it, even with sleight of hand.
Players might not want oil to be move-able early game using clay buckets because they want to gate oil further back in progression.
Etc, etc, etc.