There is quite a bit of info around this site that support that adding ATF doesn't act as a flush b/c modern ATF has less detergents than modern motor oil - seems to be a left-over from a long time ago that just persisted on. Have a look at HPL's Engine Cleaner product which would be a better way to go.Just speaking from experience, no worries, to each their own. I do use LiquiMoly Engine Flush lately thou, works very well and takes less shelve space.
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