10w 30 it is also SM rated for gas engines. It is available at Walmart in a 5 qt jug. The 15w-40 is just to viscous. The deisel oils have extra clean additives that might help the lifter issue and/or other noise. Note that these oils are not Starburst (seal on front of bottle) rated by API. Not a problem they just can't pass the economy test and they probably exceed the ZDDP % in the standard gas engine oils with the Starburst symbol.