I am in the process of cleaning about 75 Athearn HO engines (mostly diesel) and a few Rivarossi HO scale steam locomotives. All of these had been stored for maybe 10 years, probably in a hot environment like an attic. I have been disassembling and cleaning by hand with good results, but this process is fairly slow. I am curious if it would be safe to use an ultrasonic cleaner on a major portion of each engine. I have seen periodic mention of using ultrasonic cleaners, but I'm uncertain of what parts/assemblies can be safely put in an ultrasonic cleaner. Taken to the extreme, I have seen advertisements that show entire engines placed in an ultrasonic cleaner. I'm also curious what cleaners and/or detergents are recommended for such an ultrasonic cleaning operation.