I did 4 caps to 4 gal water. Maybe the water was too hard.
I heard somebody say the Windex glass cleaner has Ammonia which is bad for stainless steel, so I don't use it.
I just got a water spot remover by Chemical Guy, I will try it later.
No, it doesn't cause the water spots, it is just not good enough for removing all the water spots caused by hard water, so I use it to clean most of the parts and try to find another solution to remove the water spots.
They will let you only check the exterior, I think the main thing is the panel alignment, after that, if you accept the condition, you will set your phone as the phone fab, and then you can open the door to get into the vehicle.