Long story short I am a HUGE fallout nerd and recently got my fiancé into the show and convinced her to dress up as Vault Dwellers for my local Ren Fair for Time Travelers Weekend. I have most of our costumes done but I'm having a hard time finding a semi permanent way to weather our vault suits.
They are the basic ones you can buy off of Amazon from Miccostumes (for now, i have a later plan to make them from scratch in the future. Since I don't have the money for it at the moment this was my best option). I am going to replace the numbers on the backs of the suits to match the specific vault we are going for since we are in a state that (canonically) only has 1 vault.
I want the suits to looks like they are somewhat motor oil, engine/mechanical grease, car/axle grease, and other engine fluids with having the option of giving them a thorough wash to get everything out if it doesn't look very good or i decide to go with a somewhat clean look. Any advice and options would be greatly appreciated.