Big update!!
So I finished up the washing and got the winter coat on, then put some wash on spots of that.
First, a comparison between the freshly-glossed tank and the post-wash tank. The lower hull got a lot of it obviously. Not sure why the wash isn't appearing on the side with "First In Bastogne," but it's definitely there.
Here's a walkaround. I really like how the engine deck turned out.
Here's a shot of the tracks. I used Mig's track wash for the metal ends since the center parts of the tracks were rubber, at least outside. I am kinda bummed as I mentioned before that these tracks aren't actually the correct ones, but they will have to do!
Then came the winter wash! I was especially worried about this part; I used a recipe of Mig's Light Dust pigment, flat white acrylic paint, and distilled water. I derived this from this thread, so credit goes to this guy who wrote it (Proud Kraut is the username):
http://www.usmilitariaforum.com/forums/index.php?/topic/126652-sherman-m4a3e2-jumbo-cobra-king/ I don't think mine is as refined and smooth as his. :P
So I experimented with the portions for a while until I got it just right. I used the inside of the lower hull as a testbed since it won't be seen on the finished model. Here it is after I finished experimenting with final oil washes the other night... Messy!
Finally got the mixture right and this is what it looked like.
So then I threw it all over the tank! Another walkaround. I don't particularly like the splotchy look but I couldn't figure out how to achieve a smoother finish. Like I said, the other guy did it much smoother than mine. :P I made sure to pay as close attention as I could to the historical photo; for example, the front of the tank is more white than the rest.
After that I debated on whether or not to give it more oil/dirt "stains" by way of washes. I again tested my theories on the inner hull (as shown above) and decided that it would work if I was very modest with how much wash I put on. As you could see in the testbed photo, the darker and stranger-looking spots were spots with a lot of wash put on. The more realistic and brown/green-ish spots were made with very little wash.
At this point I noticed the front of the tank has differing amounts of the winter coat on. The glacis plate is much lighter, while the transmission armor is much darker with less wash on it. I ended up addressing this in the following set of images; I unwittingly blended the color difference together by semi-cleverly applied stains!