Yup, not happy with the durability of MG#21. Lucky for me, manage to finish 3/4 of my 1L bottle of MG#21 better the formulation broke up (turned to paste and water). Anyway, lucky you sold them off......
Nothing to do with your new car paint. Like what bro. kris mentioned, it is the surface prep. New or old, surface prep is the most important. Wax and sealant is just to protect what you have shined up, and what you shine is your surface prep.
>>>When it squeaks, no more wax<<<
Not necessary. Some says after your wash, when you dry the car, is the cloth dirty? If yes, then really no more wax. If still clean, then there is still protect as dirt is not sticking on.
When you do you shampoo wash, makes sure the dilution is correct. Too light and it would clean. Too strong and some wax will go with it and you may get the squeaky panel.
I have tested many dilutions and the problem is different shampoos comes with different strength therefore the dilution is different. You will have to test it out with the shampoo you are using. Since you are getting the squeaky feeling, maybe you should dilute your shampoo strength further......