@JeremyECrawford When splashing oil on someone, is it autohit in melee range, or do you still have to make an attack roll?
— Etan Falu (@BerrickLune) April 25, 2018
Whether you're trying to splash oil on someone or hurl a flask of oil at them, you need to make a ranged attack, as described in the text on oil (PH, 152). #DnD https://t.co/RxxQmGFtCS
— Jeremy Crawford (@JeremyECrawford) April 25, 2018
Thank you for this clarification. I literally joined just to be able to ask questions like this. Thank you for interacting with your players! my pleasure! And welcome aboard!
— Jeremy Crawford (@JeremyECrawford) April 25, 2018
To be clear to readers who may be unaware, this means the attack roll in melee is at disadvantage due to being a ranged attack. That is, unless the attacker with oil has the crossbow expert feat, I believe.