Red boxcar colors

[doctorwayne]

You can use almost any colour to alter a basic "boxcar red". I usually batch-paint cars, and even if they're similar cars for the same railroad, often alter the colour as I paint: paint 3 cars, add a little orange, paint 2 more, add some yellow, paint a few more, add some black, and so on. Cars from the same order may look the same when they leave the builder, but they don't necessarily all go into the same type of service or all run in the same geographical area, so they're unlikely to weather in a similar manner.
To make a car look new-ish, but not brand new, thin some of your basic colour (or one of the tinted versions) very severely (90-95% thinner), then make some light passes over the entire lettered car - this lessens the contrast between the white lettering and dark background just enough to remove that "too new" look.
For a slightly more weathered look, use a similarly-thinned darker colour (brown, grey, black, or even a darkened version of the car's base colour), then hold a piece of cardstock against the car at its vertical rivet lines and make a light vertical pass, aimed at the point where the card touches the car. Move to the next rivet strip and repeat. Since riveted panels usually overlap in opposite directions on either side of the door, be sure to reverse the position of the card to account for that - in other words, spray the "dirt" on either the lapped panels, or on the ones doing the lapping.
This B&O boxcar car shows this type of panel-shading, although it's also had more weathering applied over it:



...and another:



Outside post-style cars, as in your example, can be weathered in the same manner, but the "dirt" can be applied to both sides of the posts, with only the posts covered - they seem to stay cleaner than the inset panels. A little kicked-up road dust and grime sprayed along the lower extremities of the car and its trucks and frame will help to blend the different colours together.

Wayne