St. Peter's Keys
St. Peter was appointed by Christ as the first pope of the church, and the keys signify his authority as its first prelate and the authority of the church to bind and loose -- basically to open and close the gates of heaven. This is essentially what gives the church the authority to administer the sacrament of reconciliation and thus forgive sins, opening the gates to heaven for the penitent.
St. Peter is an enormously popular saint who is called on for all kinds of things. He's an ally when you need a road or doorway opened (or closed!), and he's the patron of locksmiths and popes. He's called on by leaders and by anyone who needs discernment, wisdom, courage, and/or clarity of insight, especially when at a figurative crossroads.
His reputation for removing obstacles and opening roads towards your goals is legendary, and he can be an ally in nearly any situation where someone is metaphorically doing some gatekeeping and trying to keep you out. He can help you overcome to attain success, knowledge, and freedom.
Esoterically, some interpret the power of binding and loosing to put this work in the arena of the magician and sorcerer, and use the crossroads and keys symbolism to loosen strictures they want to be free of as well as to bind their enemies from taking action or doing further harm. So there are certainly associations here with protection, in a particular sense, as well as with occult wisdom and mastery and gaining access to hidden realms and sources of knowledge.
And of course this sort of work could easily and intuitively be adapted for goals related to safe travel, having your activities and movements overlooked or ignored by enemies or authority figures, and any work related to divination.
You can use this oil to dress mojos, amulets, objects, and candles, or simply as on offering to St. Peter.
In some houses and temples, St. Peter is associated with the lwa Legba.