No, it is not necessary. Several use as a maintenance or repair item with good results, but there are others that have experienced problems. Engine flushes have their place in the maintenance/repair world, but the idea is to use a quality oil and filter and hope to not run into any issues.
can crack the engine.
Do you mean flush the oil (not recommended) or flush the coolant?
No they are completely different. A engine flush will only clean the engine a transmission flush will only clean the transmission. These two components use two different kinds on fluid therefor they can not be mixed together.
Not far, anyway. The engine flush is not engine oil ... its only purpose is to, hopefully, clean the inside of the engine areas. That's why it's called "Engine Flush" and not "Engine Oil". Get it out and put the new oil in soon.
Add Engine Flush to the motor oil at running temperature before changing the oil. After adding the product, allow the engine to idle for approx. 10 minutes. Then change the oil and the filter. Engine Flush is compatible with all commercially available motor oils. We recommend cleaning the engine interior with Engine Flush before every oil change.
You will not damage the engine but you can damage the radiator if you use any high pressure. If you only flush and apply no pressure you will do no damage. Use a chemical flush and a water hose and you will be safe.
To flush an engine of coolant in the engine of a Kian Spectra refer to the manual. Auto manuals can be purchased at auto part retails or in bookstores.
Bring to a shop that has the necessary equipment
You still need to flush the engine block and heater core.
An engine flush can be done by draining the coolant system. Disconnect the top and bottom radiator hoses, and keep filling the top hose outlet with the engine running, allowing the water to run through and flush the system. Take care to not run the engine too long or it will overheat.
I do it befor every oil change, and my engine is very silent
A semi flush uses about half the water that a full flush uses. This saves using water when it is not necessary to use more than is required. It saves money plus helps the environment.