welcome to the forum, and glad you found your way to this part.
I recently did a real thorough cleaning of this set, though in olive green. I’ll be doing a mojave set next winter. But the steps would be the same.
first, honestly assess the condition of the cars, and how important it is for you to get them as close to new. For me, it wasn’t my first attempt, so I went all out.
I disassemble as much as possible. Taking off roofs, trucks, and decided to replace most of the couplers, and the ones I kept i wanted to shine. I even took the air tanks off the of the bodies, just be careful not to break the tabs that hold them in place. Also, you may need new washers for the trucks if they have those horse shoe shaped ones.
Next I took the wheels off the trucks. Soaked all of the the metal parts i was saving, wheels, axles, couplers, and roof screws in mineral spirits over night. The next day I cleaned with a shop cloth then a wire bruch on the dremel. All brightened very quickly. I then sprayed with wd40 and wiped down with a cloth again and put them aside.
The only real metal trim piece on these cars is the nickle ends to the air tanks. I removed these from the air tanks, again being gentle with the tabs. Mine weren’t bad, just oxidized. I used some Mother’s Mag polish (found in auto supply stores) on them with the soft buffer wheel on the dremel. Took a few buffer wheels to do them all as the Mother’s mag polish turns it all a bit black before it returns it to a bright shine. It takes some time, but really looks nice. I then put the end back on the air tanks that i had just cleaned with a damp cloth.
Now for the painted pieces. Be very careful with this. In some ways this 80-year old paint is tough, but in other ways it can easily be ruined. The one thing you do not want to do is clean the painted surfaces with detergent or water. If there is any visible dirt, a damp cloth, and i always start on the dry side, should do. To bring out the luster,