Bountiful Bottle

[Lord Lupus the Grey]

Mythic item. Can it be used to double the effect of oils, not only potions?

Thanks!

[Archaeik]

RAW, no, BB expressly functions on water and not oil.
Oils are also distinct from potions despite sharing item creation rules... any interpretation that suggests the bottle could be used for oils must also assume that they aren't included in the description for brevity or forgetfulness, which would require input from the author (but that input would not change RAW or be considered authoritative).

It's likely not mechanically problematic to allow it to function with oils as a houserule.