I drive my Scooby very hard and I am beyond stage 2 power levels. I run T6 and check the oil every 1000 miles or so. At most I have to add about 1/8 of a Qt. after about 1000-2000 miles. I run my T6 to about 5000-6000 miles as well depending on how I have driven the car. My car has 20K+ HARD miles and its running like a champ.
I cannot even fathom how a car gets 4 QTs low on oil and not noticed. There would be a difference in how the car runs, power, noise, and operating temperature. Even when I was a noob and ran Mobil1 5w30 in my 2010 WRX I saw it 1/2 QT low after 1000 miles and after 3750 miles noticed that adding 2.5 QTs of oil over time was not right. I changed to T6 and never burned oil like that again. In fact I am using oil, not burning oil, but most subies use a little oil.
4QTs blows my mind.