New Quaker State Oil w/ Zinc

Another oil story
Back in the late 80s my dad had a buddy who had a 77 charger Daytona with a 400, that I believe he had bought new
He worked at Sears and often had us (I worked in the shop there at sears at the time) and raved about the Sears spectrum motor oil and was fine with us using that in his car.
Also said (didn't ever really complain about it) that this car would use about 2 quarts between oil changes. Though he lived a mile from work if that.
For some reason we were out of his usual oil, (which was what we put in every oil change we did unless the customer requested something else)
He was quite good about coming in at every 3000 miles. This time we put Valvoline in there, and he was getting the car ready for a trip to Florida.
He came back about 10 days later for another oil change. This time requested Valvoline. Said that all the way down and back the car didn't use a drop of oil with the Valvoline in there. Was a pretty good car, I don't remember him ever really having much problems with it.