ultrasonic cleaner solution

I have a small ultrasonic cleaner from HF. I have found that it doesn't work Magix but it does speed up my rate of cleaning. I can put parts in vinegar/gasoline/diesel in a container for 10-12 hours, or achieve similar results in about 2-4 hours in the ultrasonic cleaner. I have little cake tins that fit perfectly inside the ultrasonic cleaner tray so that I can just clean those rather than the whole unit itself (so much easier this way) I usually run just enough water to get about 1/2 of the way up the tray.
I have used it to degrease(gasoline) or to clean and unfreeze rusty bolts (diesel or white vinegar) for vintage bicycle parts, basic automotive hardware, and old small tools like files thay I have gotten at garage sales but not done much carb stuff in it yet because I doubt it's big enough to fit the whole carb I'm.
I tried using glass jars but I wasn't a fan because I found its better to spread everything apart flat along the bottom of the tray.