prepping Postwar and MTH locomotives an rolling stock for long term storage.

Remove the batteries if they are removable. I leave Nickel metal Hydride batteries in and charge/run once a year. Depends on how long they will be stored.

If not storing them in there original boxes to start, be careful of the wrap material. some bubble plastic or soft shelf liner material will stick to the finish. Use strong storage bins and they have products that keep out moisture.

Use the acid free wrap that gift stores sell for the post war trains. Store everything in the big rubber maid type plastic bins with a lid. 

Rob

For long term storage, you'll never get a drying agent that will last without a 100% seal, something that's almost impossible to do.

I'd probably put them into storage that I could install a Golden Rod Dehumidifier in to keep them from moisture damage.  I've had one of these in my gun safe for many years.

I wouldn't wrap plastic directly against an engine or car; first wrap in tissue paper like for wrapping presents, then bubble wrap before putting it in a carton for long-term storage, ... after removing the battery.

Long-term meaning months ....