Originally Posted by Remerson228
Yes, your truck requires the use of 5W-20 for proper operation of the MDS system. The tick you hear is likely what's commonly called the "Hemi tick". They all do it. There's no need to change the oil any sooner because of the lower viscosity. The engine was designed and built to accomodate this oil. Running the 5W-30 will hamper the MDS operation.
If that is the case that the hemi needs 5w20 for the mds to work why is it that hemi's with mds outside of North America call for 5w30. These are the same engines with the only exception that in North America we rely on CAFE standards and it is proven that 5w20 improves fuel economy marginally. The unknown part is the effect on the engines longevity.