We've got a '94 Jeep Grand Cherokee Laredo approaching 200,000 miles. Same Engine and Tranny. We have however started running 93 octane gasoline in it. The Jeep had started knocking and was loud at interstate speed so we did some experimenting ran some cleaner through the tank and started running the expensive stuff. Cleared it up and now runs just like new.

Oh its the straight 6 that's now being discontinued due to it no longer being able to meet the strict emissions standards. Farewell straight 6 you've been a great engine in many Jeeps, for many years.