I was wondering if there is anything out there that you all use to clean the axle, frame etc. with, that will turn it back to black again. I hate getting my truck all clean and then when the sun starts to set the underneath sticks out like a sore thumb. My truck has never been taken offroad, nor do we have much snow/salt down here in oklahoma so it isnt rust. It is just dirty greyish brown looking. What do you all suggest?

You can kinda tell what im talking about in this photo- i.e axle, wheel wells

 

Some soap or degreaser. A good pressure wash. Let dry. Then hit it up with some flat black spray paint.

EXAMPLE
Decided to paint the axle

 

Im not much into painting the undercarriage. I think it looks so tacky when i see that someone painted theres and missed spots or just got it too shiney.

 

Guess i should have looked at the thread first before replying. lol that looks great

 

I used some flat black spray paint on the axle. Looks great. Not tacky at all. And no, I didn't remove anything. Just taped off a few things. Took 10 mins total.

Edit: P.s. I painted it last July, Not a single chip in the paint. Still looks exactly as it did when it was first painted. I too care what the underside looks like. Especially the rear since it's easy to see under there. I also keep the entire tailpipe looking as it just came off the show room floor. I sand it wish some extremely fine paper every couple months and keep a very light coating of wd40 on there in between. Truck looks brand new from behind.

 

Painted all that and not the tail pipe? Helps "hide" it, especially when it starts getting that rusty color.

 

I was thinking of doing some high temp. clear on the tailpipe, but I sand it with like 220 grit paper every once and a while and keep a light coating of wd40 on it at all times. Always looks brand new.