In my many years as a pump jockey/mek-a-nick, I always put 5 quarts of
oil in a stock SBF, with the filter change. Ran across very few cars that required more, with stock
oil pans and systems. I'm thinking that you're thinking wrong. The minimal amount of additional
oil needed for the lines going to an external oil filter would probably be less than 4 oz. unless they are REAL long.