Have you tried Maxlife Full synthetic? My 4.0L doesn’t burn or leak any oil but since it’s got almost 100K I figure why not. Back when I had my beloved 3.4L I ran Mobil HM with 190K.I use either M1 or Valvoline Synthetic in my 4.0 Tacoma. I guess in 300k + miles I'll find out if the Valvoline was good or not