Are you referring to a summoning triangle a la goetia or do you mean the oil should be left within the circle of the sigil? Sorry, I couldn’t quite tell. If the former, I wasn’t planning on doing a full blown summoning (nor would I know how to go about one) as of yet, just a bit of pendulum divination, which I was probably going to start doing regardless. My Crowley/Thoth Tarot deck arrived today, which I did a couple of 3 card spreads with and got alright results, but I’m too inexperienced atm.

Yes. If you do go ahead with a goetic summoning, as clarification to my previous instruction, create the sigil, paper is fine, anoint the sigil with the oil if you have it, and leave it in the triangle during the summoning for the spirit to have access.