Washing my StuG - surgical or all over?

Hi all,

I normally use a slap-it-all-over watercolor wash (usually sepia) to wash my armor. This time I'm going to try an oil wash in mineral spirits given the results I have seen in various places. I've painted the vehicle dark yellow with a red-brown and dark-green camo pattern. The questions I have are:

1. What color for the wash? I've heard it recommended that Burnt Umber oil or B.U. darkened with black makes for a nice effect -would this be appropriate for my Stug? Would another color be better?

2. Should the wash be applied "surgically" just to the details and crevices or should it be applied over the entire vehicle (as mentioned in FSM) and then any adjustments gently made with a brush dampened with spirits? There seems to be two schools of thought with regard to this - which works best?

With the watercolor wash I've done, I usually just slap it all over since it gives the vehicle a nice overall dirty look as well as accenting the details.

Any of your thoughts or opinions would be terrific. Many Thanks.

Jim