You make me cringe so much. I'm assuming you're new to owning Glocks, so I'll give you some slack.
1) Ultrasonic cleaning and Glocks don't go together. It's known that some solutions (ammonia-based, if I recall) will destroy the bonded black coating off the tenifered steel. So, I'll repeat it: Ultrasonics and Glocks don't go together (God help you if you shoot a Glock and there is still residual fluid in the striker assembly)
2) It's a freakin Glock. Since it's a Gen4 model, I'm kinda guessing you haven't had it long. Unless you have a Glock that's had 20000 rounds down it and it's never been cleaned, I cannot see a reason why you would even consider an Ultrasonic, and even if I did, I wouldn't drop the slide in it - ever.
3) Properly cleaning a Glock is dead easy. Here's an article that shows you how to do all the cleaning you should ever need to do on a Glock (Cornered Cat - Gun Cleaning 102 (Glock)
). Most times after I go to the range, I'll disassemble, brush out the barrel with Gunzilla or CLR, wipe the frame down with a clean cloth, and reassemble. No oiling, etc. It's a Glock.