I've got many of the basics done, like cap, rotor, plugs, and wires... but what else should I do for a general tuneup at this point in its history? I am a new owner, so I don't have a full list of what has been done or when, but I want this thing to last for a long time.

 

Check/replace all fluids & filters, fan clutch, hoses. Check/replace/lubricate all steering, suspension, and drive shaft joints. Check/clean/replace battery cable connections, PCV valve, bulbs & sockets. Just to name a few.

 

Make sure your cooling system is working well. Look for leaks. How does the radiator fluid look (green or brown)? Then flush the cooling system anyway, just to get new fluid in there and wash out the sediments. Plenty of threads explaining how to do it. Make sure the water pump is working well too - turn on the heat on high and see how much heat you get - it should be blasting hot air, if not the water pump may be done or the heater core is clogged. The cooling system is often neglected, especially if you are thinking of selling the vehicle.

Being you are in CA I doubt you have any significant rust, but look underneath anyway.

At 216,000 miles the differential bearings may be getting to the end of their lives and the pinion seals will probably be leaking. If the leaks are minor, don't just dive in and change them because it will upset the careful end of life balance of the pinion bearings and they will start to make noise and will eventually need replacing, a major PITA, and expensive if you don't know what you are doing.

 

200K miles is a fair amount for any car.

Most service intervals on the jeep are 60K miles so I would start with changing pretty much every serviceable part.

1. Basic tune-up and oil change first (ignition system and clean all engine electrical connectors, grounds especially, clean throttle body and intake system, new air filter if needed). Use Wix 51515 or Napa Gold 1515 oil filter and a Wix air filters + Rotella T6 5w40 if your oil pressure is not great at hot-idle.

2. Change all of the rest of the fluids (T-Case, Transmission, Differentials, and Brake fluid). Clean and degrease engine bay and driveline components with degreaser after changing the fluids, to help spot any leaks.

3. Cooling system upgrades (I would change water pump, thermostat, hoses, flush cooling system thoroughly including gentle backflush of the heater core, and a new Goodyear Gatorback drive belt). You may opt to replace the radiator if it looks like it is original (scale build-up clogs the tiny passages inside). Do this before your thermostat/water pump fails and you end up cracking the head.

That should only cost you $1-200 bucks at the most. If any fluid comes out grimy, change it again after 1-2000 miles as most people think you only need to change the oil and not any other serviceable fluid/part


After all of that, I am sure you will want to do driveline, suspension, and brake components which should only really cost you another couple hundred bucks. At some point, splurge on new injectors and o2 sensors if your mileage doesn't seem to be that great. Do it in stages month to month, so it doesn't hurt your bank account and so you don't end up having to do all the work at once, drive it and prioritize repairs based on safety and whatever is worn out the most.