Powers or Items used outside encounters

Question

As a player and DM I am not quite sure how to approach the perspective of powers or items used in a non-encounter situation. For example, I just saw that the alchemical item slow-step oil can be used as an encounter action and applies to "the next creature you hit"; it does not require the attack to be on the next turn or anything, like many other powers or items.

That being said, could a player coat his weapon with slow-step oil and keep it indefinitely until he hits with that weapon ?

The same kind of question goes for Corrosive Oil or other similar items/powers, where there's no restrictions on when to apply it's effect.

Answer 1

The rules are vague

Unfortunately the entry for Consumables in the Rules Compendium is full of wit and fluff and completely devoid of any rules whatsoever.

However, as NikolaiDante notes any powers used that have lasting effects will only have those effects continue until the encounter ends.

Beyond that we can look at the rules for Poisons, most of which are consumable items to shed some light on the issue:

Apply a Poison: Apply poison to a weapon. This is a standard action. Poison applied to a weapon loses its potency at the end of the encounter or after 5 minutes have passed.

PCs could apply item consumables to their armor and weapons prior to a fight, but it better be right before or they will wear off and lose their potency before they can be helpful.

As Brian points out, "Generally, things with "encounter" duration will last for 5 minutes outside an encounter (I don't know of any exceptions). For examples of powers, see Warlock's "Shadow Form" and "Wings of the Fiend", Warforged's "Empathic Resonance", Half-Elf's "Persuasive Words", and Ranger's "Forest Ghost"."

Answer 2

First of all, I disagree that they are "encounter" powers. I don't see that term (or even the red colour) anywhere near alchemical items.

"All alchemical items are consumable. An item is expended when put into use, although its effects might last well beyond the time when it is applied or otherwise employed." - MME

That was a perfect opportunity to state that alchemical items have a hard 5 minute time limit. The fact that the oils are standard actions would make them absolutely useless in combat unless they can be applied during a short rest.

Alchemical items are a significant money drain as it is. I don't see the need to make them suckier.