used oil analysis have shown that the Grand Cherokee's flat tappet 4.0 does NOT like M1, producing more than twice the iron than any other oil tested.
Valvoline conventional, Super Tech Syn, and Amsoil have all shown very good used oil analysis.
The Wrangler likes all the oils tested, including the M1.
Valvoline conventional, Super Tech Syn, and Amsoil have all shown very good used oil analysis.
The Wrangler likes all the oils tested, including the M1.