hi Matt,
i am an old school modeler just so you know, i like to drybrush which is "out of fashion" for some and i try to weather right to the edge without covering the whole piece in mud. the suggestion to add a wash is just to add a bit more dimension to an already great model.
if you would like my opinion, i would use oil piants and mix raw umber with a touch of burnt sienna thinned with turpentine to make a weak wash that i would apply around the bolt head, edges, creases and recesses. i would use a clean brush damp with turp to blend this wash and to remove any tidemarks.
a quick search on this site found this article
https://armorama.kitmaker.net//features/782 washes are a fairly easy technique to master and can add a new level to your models. how much you use this and how many various colours/stages/transparent filters/oil spills you decide to go with is up to you... you may like the results or you may not. like many things, having the tool in the toolbox is handy, knowing how to use it is handy, but deciding when is the best time to grab it from the box is open to debate. cheers, bd.