Did the turbo trans ams come stock with a roller cam? Because thats the only way you dont need zddp. Any car with a flat tappet no matter what the spring pressure should use zddp so you dont eat a cam and kill a motor. I think i remember reading on a dealership brosure that the turbo ta came equiped with a roller cam. I own a 3500 mile tta and use a bottle of zddp every time i change the oil in the car just for extra security.