Some people trust Shell Rotella T6 to protect gasoline engines with flat tappet camshafts, provided the viscosity is suitable. Although T6 has good zinc and phosphorus levels, these engines don't require its high detergent, which can reduce zinc/phosphorus effectiveness in gas engines. Additionally, T6 lacks friction modifiers (it's wet clutch compatible), which are desirable in this application. In a gasoline engine with a flat tappet camshaft: 1. What are the implications of the lack of friction modifiers? 2. I've understood that Shell Rotella T6 has about 1100 ppm phosphorus and 1300 ppm zinc (equivalent to M1 TDT). What would be the implications of using S-rated oil with 100 ppm less phosphorus and 200 ppm less zinc? 3. Would T6's high detergent levels and lack of friction modifiers cause you concern?