I'm looking to make some cuts in a 55 gallon oil drum and I'm trying to avoid getting blown up.

First of all the drum is closed end with two bungs (one large, one small). From what I can tell it had almond oil in it before I picked it up. There is some remaining oil in the bottom.

I want to cut a door in the side of the drum and turn it into a bbq. I'm probably going to use abrasive cutoff disks in my angle grinder so there will be a lot of sparks and I'm worried about igniting the oil in a confined space.

Does anyone have any advice for cleaning the barrel out or any other suggestions for how I should go about doing this? Thanks.