Gear bay washes

I finished up a 1/48 F-18F and used a dark brown wash in the wheel bays:

I use two washes sometimes- a dark gray and a reddish one to simulate hydraulic fluid.

Thanks for all the quick responses! I think I 'm gonna go for a brown wash.  I would like the aircraft to be a bit dirty.  This is my first build in a long time and am trying many new techniques so we'll see how it goes.  I will try and post some images as well if anyone is interested.

Modern US made military aircraft have white gear.  A light brown or light gray wash over it. 

The following photo is the gear well of a B-58. The well is clean with a light coating of dirt/dust. I think that the ground crews keep the gear well clean so that they can easily look for leaks. If I was doing a moderen aircraft I would paint the gear well with an aluminum color paint and use a rust colored wash. 

For white i would go with a light grey pin wash.