Come on, don't be silly by wasting your money in so called "coating". Especially sierra slow. It's a rip off and scam.
And also "glass coating" which is a useless as u need to do maintenance to protect the coating to protect the paint. Economy is not good so cash is king. Just wash as usual and if it's really an eye sore go and repaint your car after a couple of years. One layer paint will only cost less than RM2k and your car will look brand new and shiny again.