Short answer: currently 24 quarts.
The Corvette and Tacoma both call for 5w30 and have 5 quarts M1, 10 quarts M1EP and a random 5 quarts of M1 10w30 (will use that in the Corvette, it runs hot by design). The bikes run 10w40 and have 1 gallon of Rotella T6 for those.
The most I've ever had stashed at one time was 30 quarts (6 x 5qt jugs).
The Corvette and Tacoma both call for 5w30 and have 5 quarts M1, 10 quarts M1EP and a random 5 quarts of M1 10w30 (will use that in the Corvette, it runs hot by design). The bikes run 10w40 and have 1 gallon of Rotella T6 for those.
The most I've ever had stashed at one time was 30 quarts (6 x 5qt jugs).