I responded to a thread on another forum about using 5w-20 in an engine that specs 5w-30. To my knowledge, Ford back-spec'd several of their motors to 5w-20. Again to my knowledge, they specifically stated that the SOHC 4.0 v6 (used in the Explorer and 2001+ Ranger) should continue to use 5w-30. Please follow the attached link and set me straight. http://www.ranger-forums.com/f15/dealer-put-5w20-insted-5w30-113471/