4 1/2 or 5 quarts of oil with 1/2 quart of ZZDP?

DartGTDan said
I will be changing the oil & filter in my 318 shortly. My engine builder told me to include a 16 ounce bottle of a ZZDP oil additive with the fresh oil and new filter.

My question is do I use 5 quarts of oil + 1/2 quart of ZZDP additive?

Or, 4 1/2 quarts of oil & 1/2 quart of ZZDP equaling 5 total quarts?
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You do not want to exceed 5 quarts of any product in a stock oil pan other wise you will suffer power loses from windage.
Mix the whole mess together and fill the crankcase to the proper level, keep the rest of it for make up oil.