Is good idea to use engine flush additives? for example 5 min flush before oil change.
No. Modern reputable-brand engine oils have the capability of keeping debris in suspension for some time, the important thing is getting the engine hot and then empty the old oil. Drain it thoroughly while on flat surface, replace the oil filter and drain plug, fill with fresh oil, start the engine for a minute ore two, shut off, let sit for another minute or two, check the dipstick, top up to the MAX level mark. Do it at Manufacturer-specified intervals, NOT SOONER (another waste of money).
If you use cheaper/conventional motor oils that are prone to sludge, yes, I would recommend it. If you use a good synthetic you will probably not need it.
never a good idea to flush an engine.
