In my way of thinking, there are two goals that you may be wanting to achieve with diesel fuel additives; lubricity and cleanliness.
Just a smidgeon of oil will do for lubricity if you have an older (123) pump that has not been upgraded with hardened barrels. There is no need for ATF, and certainly not that much of it. A few ounces per tankful would be enough.
The second, cleanliness, can be accomplished by any number of good additives on the market, with Redline certainly being at or near the top of the list.
In the sixties, when most additives were snake oil of somekind, ATF was used for cleaning things because it had lots of detergents. What they called "high detergent" oil was just coming into use. ATF was used to keep crankcases among other mechanical things clean. With the motor oils we have now, which are light years ahead of then, there is no need for using ATF for anything other than AT's. ATF can even cause harm to some things, such as power steering systems. Modern ATF has evolved into such a special purpose fluid that it's additives are not good for seals in other systems.
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