COSXJFAN

My XJ shows 187,000 miles on the clock. When I bought it I noticed that it had a light harness rolled up and stuffed by the airbox for towing behind a vehicle or RV. It made me start to think that my XJ may not have as many actual miles on it as I thought. I have been keeping an eye on things to see if I could support my thoughts about it or not. The only thing that I have been able to look at is the condition of the oil. I change my oil every 3000 miles. At this point it has been gold up until it's time to change it. I don't use synthetic oil, because I have heard that it is not good to switch a high milage vehicle over to it if it has been on conventional oil it's whole life. Which brings up another question. Is this theory BS or what? Anyway, judging by the color of my oil after 3000 miles of use don't think I have as many miles as I thought I did. I don't have as many leaks as my other XJ did, as well as the usual low end clunk at idle that most XJs have at this amount of milage. Are there any other things I could look at to tell me this? I don't have a compression tester so that is not an option. I thought you guys might be able to point me in the right direction. Thanks guys!!

xjjeepthing

45,859. Only had 19,580 on it when I bought it.

nick_n_ii

My ZJ has 190K on the body, 100K motor, 60K trans, 40K T-case.. Ya that's about it....

COSXJFAN

????wha????

drakan1908

I've heard the same thing about the oil so I just stay with conventional motor oil and I change 3000 miles or 3 months. Usually 3 months because I do a lot of short stop and go driving. As far as wear on the motor,a compression test is the only way I can think of to tell how much wear on motor besides visual inspection but some one with more mechanical experience might know of another way. Is it possible to talk to previous owner?

nad

What year is it? I bet it does really have that many miles on it. Especially if it's an 80s, early 90s model.

BlueXJ

My '90 has 267,000 on the odometer. New engine at 211.000 so that may change your calculations somewhat. Been on full synthetic since breakin. Now has the larger oil filter done when at about 20,000 on the new engine.
No problems to report. Still runs around 40# oil pressure at operating temperature, and about 65# when cold.

whowey

The theory about synth oils in older motors is garbage.

How it got its start...

As a motor ages the seals shrink/degrade/wear out.
Good synthetics have much higher cleaning properties and smaller molecules than pure dino oils...

As the synthetics clean out the crud, dirt, sludge, mung, etc. left behind by the miles and miles of dino usage, leaks will appear. These leaks are not caused by the synthetic oils, but were actually pre-existing. Many people too lazy to maintain their rigs properly would rather blame the sythetic oil for doing exactly what it was designed to do than fix the problem in the first place.

But if your Jeep was used as a tow-behind... I wouldn't worry about it. The engine/transmission/transfer case didnt accumulate any wear during that operation. And normally RV'ers take VERY good care of their equipment. When you put the transfer case into neutral, the Speedometer and odometer do not move, so no miles are racked up. Its ease of set-up behind motor homes is on the reasons the XJ was VERY popular with the RV crowd, and the Jeep line in particular remains popular. Some friends went to get a new vehicle for a DD, but they have an RV and wanted something to tow behind it that was easy to setup, and didn't need alot of extra equipment. They live in Midwest so 4wd/AWD was must for winter travel. They went to every brand of car dealer around.. The choices came down to Ford Escape or a Jeep vehicle. After driving the Escape, they came home with a brand new WK...

A compression test and a leak-down test are two of the tests for getting a better idea of the internal condition of your motor.. A compression tester is available for less than $50 from the major parts stores or Harbor Freight. You don't need a Snap-on unit for your personal use. I have a Craftsman unit I've had for probably close to 15 years.. It's not like it's a screwdriver you are going to have out on every job...

Bent/Bolt

258,877 on my 91 cherokee

BlueXJ

Great first post for ya there Bent/Bolt. Glad you are on the forum. Welcome, Now go to the "Introductions" page and properly introduce yourself so everyone can welcome you properly in the correct thread.

COSXJFAN

Word!!