'03 Laredo w/ the 4.0 176K, I'm assuming it's the original engine. I doubt the original trans would have made it this far, but I have no idea if it's been rebuilt/replaced. Everything under the hood and body looks clean and original, so who knows....
I just got it 4 months ago, so I have no idea of what was used for oil or how often it was changed. I can say this; when I replaced the valve cover gasket, there was absolutely no carbon build up or sludge anywhere on the head.
I did an engine flush using BG chemicals 'engine flush'. Everything came out looking good, no nasty gunk or sludge. I used Pennzoil high-mileage oil and a Mopar oil filter. I plan on doing 5K intervals for the engine oil changes.
I've had to change the PCM, the oil pan gasket, V/C gasket, both idler wheels for the drive belt. I replaced the fuel filter ( Wix), air filter (Wix) and recently, the spark plugs. Those last pieces all seemed to be original parts, so I wonder if the poor Jeep was ever maintained.
I also replaced both axles with ones from an '04 Overland, they only had 68K on them, it was a lot cheaper than rebuilding the original ones plus now I have Vari-lok front and rear plus a D44a in the back.
I think I'm on top of all of the immediate maintenance needs for a while, I hope I can just drive the darn thing without any headaches.
I'm a 3+ for maintenance. I don't want
to work on this thing non-stop, and I'm not out looking for every little tiny items that may show wear, but when there's something that needs attention, I'll go at it full bore and only use good quality, brand name parts. My motto: do it right once and be done with it.