Bro, if seals are already damaged / worn out, then engine flush just exposes them. It does not damage seals in any way.
If there is lots of sludge / gunk in engine, and seals are also worn out, then that sludge / gunk just conceals them and not let oil leak through them. However, when you use engine flush, it de-seats all the sludge / gunk, thereby exposing worn out seals.
Use of engine oil flush is one's matter of choice. Some use it, some do not, however, in no way, it harms engine. Some even suggest to use engine flush with every oil change.
(More info can be found at: https://blog.amsoil.com/is-an-engine-flush-good-or-bad/ )
Nope. I didn't and neither it was there. The engine is almost new.
I will be using ZIC A+ 5w-20, as long as I will keep the vehicle with me, IN SHA ALLAH, so I just used engine flush to give it a fresh start and with fresh & new engine oil grade and brand (i.e ZIC, instead of ENEOS Sustina, etc. and 5w-20, instead of 5w-30 or 0w-20)
What? Who says this?
New engines do not have any sludge. Sludge / gunk develops with the passage of time, especially, if one does not take care of its ride; oil changes + oil filter changes at regular intervals to be precise.
New engine oils, especially fully synthetic ones and from reputed brands, have excellent cleaning and detergent abilities. If you use such engine oil and drain along with oil filter, after regular intervals, then they may not even let sludge to develop and deposit. Problems arise when people use fake oils, from some abc brand, do not replace them timely and drive for many many thousand miles.