I am asking for a co-worker of mine with an Impala 3.4V6, he says he adds about a quart of oil every 2,000 miles and generally goes 5,000 between oil changes, so that's over 2qts of make up oil in a 5,000 OCI, my theory is for every qt. of oil you add before your next OCI , you can extend it another 1,000 miles, this is assuming a 4 qt sump. I didn't tell him that, but that's my new theory, any logic to this theory?