What is the manufacturer recommended octane to put in a Jeep Grand Cherokee with a 4.0?

 

87 octane is perfect for the 4.0; actually that should be OK for the 4.7 (V-8) as well.

When I had the 2002 Overland, I ran 87 almost all the time, and I also run 87 octane in the 5.7 Hemi. Never had any problems, and no need to waste an extra bunch of money on higher octane.

 

the 4.0 will run on almost anything the compression is only like 8.7 or 8.8:1 so its not a high compression engine.