1991 Jeep XJ oil change

[captainofiron]

Here is a good one for you guys to consider

the vehicle is my 1991 Jeep Cherokee XJ 4.0L 4x4, it has 297K miles on the odometer,engine is original and runs great.

Im not sure what the owners manual says about the oil, I bought the vehicle used and it didn’t include any paperwork

As stated in my Hyundai Santa Fe post, we live in Las Cruces, NM. The vehicle is my toy and I rarely drive it, it is usually in the garage, but now that its warming up I want to hit the trails.

I dont know if you all are aware but the Jeep 4.0 uses an external lubrication system to spill oil all over the outside of the engine and transmission, and the floor, haha.

But seriously its hard to stop leaks on these engines, and as such I had been running 20-50 Castrol high mileage in it. Now that I have read this forum and the main Oil academy pages, I regret using the 20-50 as when it was very cold the engine would knock a while.

Anyways, any suggestion for oil/filter?

 

[FL_Rob]

Purolator Classic .
Motorcraft.

Advance Auto red can.





Fram TG

 

[Nick R]

Rotella 10W-30 HDEO or 5W-40. And use a Mopar filter, they are purolator filters iirc and fairly inexpensive.

 

[SwampSurvivor]

The 4.0s like 40 grade oils ... not sure I'd go to a 50! RT6 5w-40 works well. I have a mix of 5w-30 and 5w-20 in mine at the moment.

In all reality, it's a Jeep 4.0. It's not picky about oil at all.

I know a lot of people who beat their jeeps up pretty hard off road, overheat, etc on cheap dino 5w-20 and they don't have any problems caused by oil.

 

[Since1941]

You could do 15w40 summer, and then winter the 5w40. I know right now actually, there is thread on Jeep forum with tons of people doing this very combo. Pick: Delo, Rotella, and some are using Delvac 1300. In the winter, switch to the 5w40 version of these. However, Mobil's 5w40 isn't Delvac, it is TDT 5W40. It has been stated, that Mobil oils cause more iron wear in these engines. However, I am not sure about their HDEO's. Never really searched for a UOA using their HDEO oils in the 4.0, and 2.5L

I am currently running 5w40 Rotella in mine up here in Ohio. Works like a charm, and starts right up every time. And, this is starting in the low teens for the past month.

I have a P1 filter on mine, but may switch, as I get some start up noise with them. Always have with all my Jeeps.

 

[KCJeep]

I'd start with a thick 10w30 like Rotella. If oil pressure is not satisfactory then try a 10w40 that runs on the lighter side . In your climate you'd probably be okay with an even stouter 40 but no need to go thicker than necessary.

As posted above the 4.0 would probably run 100k on used cooking oil but they are fun to pamper. Unless your engine is about shot I see no need or reason to run a 50 grade.

JMO.

 

[jeepman3071]

Originally Posted By: KCJeep
I'd start with a thick 10w30 like Rotella. If oil pressure is not satisfactory then try a 10w40 that runs on the lighter side . In your climate you'd probably be okay with an even stouter 40 but no need to go thicker than necessary.

As posted above the 4.0 would probably run 100k on used cooking oil but they are fun to pamper. Unless your engine is about shot I see no need or reason to run a 50 grade.

JMO.


This +1. Any good 10w30 or 10w40 should be fine.

A good filter to run is the Motorcraft FL1A. They are a bit larger so you get more oil capacity, and they cost $3.99 at WalMart. They are IMO the best filter for the price. It is basically the same as the Mopar filter inside but cheaper.

 

[captainofiron]

I think Im going to go with a 10W40 for the summer and drop her down to a 5W40 in the winter.

here in the high desert we have hot 100F+ summers, and cold subfreezing winters

This one time I was hitting the trails, and my oil pressure sensor exploded and as soon as I saw the pressure drop to zero I shut her down, all I had was some lucas oil treatment and a quart of cheapo 20W50

I was out in the middle of nowhere so no cell phone, I drove it home with just that oil treatment and oil.

it was about 20 minute drive. I thought for sure I was going to kill it, but that was a good 30K ago

 

[440Magnum]

Originally Posted By: captainofiron
Here is a good one for you guys to consider

the vehicle is my 1991 Jeep Cherokee XJ 4.0L 4x4, it has 297K miles on the odometer,engine is original and runs great.

Im not sure what the owners manual says about the oil, I bought the vehicle used and it didn’t include any paperwork

As stated in my Hyundai Santa Fe post, we live in Las Cruces, NM. The vehicle is my toy and I rarely drive it, it is usually in the garage, but now that its warming up I want to hit the trails.

I dont know if you all are aware but the Jeep 4.0 uses an external lubrication system to spill oil all over the outside of the engine and transmission, and the floor, haha.

But seriously its hard to stop leaks on these engines, and as such I had been running 20-50 Castrol high mileage in it. Now that I have read this forum and the main Oil academy pages, I regret using the 20-50 as when it was very cold the engine would knock a while.

Anyways, any suggestion for oil/filter?


A 10w40 HM oil, such as Mobil 1 or I think Valvoline Max Life comes in that grade. Jeep 4-leakers like a thicker oil even though they're spec'd for 10w30 or 5w30, but 20w50 is just a bit much IMO. Fram Ultra is a superb filter for a low cost... but NO other Frams besides the Ultra!

You could also probably fix the biggest leak by replacing the O-ring under the oil filter adaptor. The rear main is also prone to weep enough to leave spots on the ground, and of course ALL engines eventually leak at the valve cover gasket given enough time and miles... but that oil filter adaptor is prone to make puddles, not spots, on the ground.

 

[captainofiron]

Originally Posted By: 440Magnum
Originally Posted By: captainofiron
Here is a good one for you guys to consider

the vehicle is my 1991 Jeep Cherokee XJ 4.0L 4x4, it has 297K miles on the odometer,engine is original and runs great.

Im not sure what the owners manual says about the oil, I bought the vehicle used and it didn’t include any paperwork

As stated in my Hyundai Santa Fe post, we live in Las Cruces, NM. The vehicle is my toy and I rarely drive it, it is usually in the garage, but now that its warming up I want to hit the trails.

I dont know if you all are aware but the Jeep 4.0 uses an external lubrication system to spill oil all over the outside of the engine and transmission, and the floor, haha.

But seriously its hard to stop leaks on these engines, and as such I had been running 20-50 Castrol high mileage in it. Now that I have read this forum and the main Oil academy pages, I regret using the 20-50 as when it was very cold the engine would knock a while.

Anyways, any suggestion for oil/filter?


A 10w40 HM oil, such as Mobil 1 or I think Valvoline Max Life comes in that grade. Jeep 4-leakers like a thicker oil even though they're spec'd for 10w30 or 5w30, but 20w50 is just a bit much IMO. Fram Ultra is a superb filter for a low cost... but NO other Frams besides the Ultra!

You could also probably fix the biggest leak by replacing the O-ring under the oil filter adaptor. The rear main is also prone to weep enough to leave spots on the ground, and of course ALL engines eventually leak at the valve cover gasket given enough time and miles... but that oil filter adaptor is prone to make puddles, not spots, on the ground.



I think mine is mainly out of the rear main, I have replaced it twice, but nothing.

the oil filter adapter seeps through but doesnt cause puddles or spots, I think the years of caked on sludge stopped the leak.

haha 4-leaker, thats a good one

 

[wsar10]

I'll add another one for Rotella, being that it likes to leak I would go dino 10-30 or the 15-40 triple T. these engines do like there valve cover gaskets and rear main seals and filter adapter O-rings but you CAN seal them up and keep them that way,

Filters your best bang for the buck will be a NAPA gold (WIX)
or a Puralator PureOne (not the classic).

I've owned more 4.0s than I can count and used similar to the above mentioned combination on all and never had issues.

these are flat tappet type engines and like the ZDDP levels found in HDEO's.

 

[eljefino]

Originally Posted By: captainofiron
I think Im going to go with a 10W40 for the summer and drop her down to a 5W40 in the winter.


Any 5w40 you could find would be syn and better suited for summer too. I would not switch out in the spring "just because" and in fact use it year round. 10w40s are sometimes pretty cheaply made but you could circumvent that by running a 15w40-- not a poor one of the lot.

 

[jeepman3071]

Originally Posted By: captainofiron


I think mine is mainly out of the rear main, I have replaced it twice, but nothing.

the oil filter adapter seeps through but doesnt cause puddles or spots, I think the years of caked on sludge stopped the leak.

haha 4-leaker, thats a good one


If you have replaced the rear main twice and it hasn't helped I would look at your valve cover gasket. The valve cover gasket is known to leak down the back of the engine and look like a rear main seal leak, its also what usually coats the engine in oil when it leaks.

 

[Greg L]

I find that my 1991 Cherokee with almost 200k miles does very well on Valvoline MaxLife with a Purolator Filter from Kmart.

I have also used Rotella and Pennzoil...both work well.

Used the Fram TG filter before; not my favorite, but it will work in a pinch.

Have always used 10w30 in winter and 10w40 in summer. Like stated above, these 4.0 liter engines in the old jeeps like 40 wt oils.


GL

 

[Kuato]

My opinion? Those that have said Rotella T6 5w40 were spot on. Year 'round.

 

[mongo161]

Originally Posted By: Kuato
My opinion? Those that have said Rotella T6 5w40 were spot on. Year 'round.


IMO....I would not use Shell Rotella 5w-40 anytime of the year....since the engine is leaking oil. IMO...you'll leak more oil with the synthetic 5w-40 Rotella T6.

IMO....I'd run Shell Rotella T 10w-30 conventional in the winter and Rotella T 15w-40 in the summer time.

 

[bullwinkle]

I'm actually running MaxLife full syn 5W30 in the '98 in my sig, and it only has a wet spot at the front seal (knock on wood)after I replaced the VC gasket, grommets, and PCV fittings-it actually still pulls a VACUUM at the breather hose to the air cleaner-at 212K! That motor will outlast the body for sure!

 

[Zaedock]

A lot of good posts. i have nothing really to add except that the rear main, oil pan, filter o ring, and valve cover gaskets are easy to do. If you do get to do your oil pan, replace the oil pump and buy the 1 piece Felpro oil pan gasket w/ the anti crush washers. Every 2.5/4.0/258 I have done has never leaked again from the oil pan gasket.

 

[440Magnum]

Originally Posted By: mongo161
Originally Posted By: Kuato
My opinion? Those that have said Rotella T6 5w40 were spot on. Year 'round.


IMO....I would not use Shell Rotella 5w-40 anytime of the year....since the engine is leaking oil. IMO...you'll leak more oil with the synthetic 5w-40 Rotella T6.

IMO....I'd run Shell Rotella T 10w-30 conventional in the winter and Rotella T 15w-40 in the summer time.



I have to tell you that Rotella T-6 has NEVER accelerated or aggravated a leak for me. I've run it for a while, then switched to M1 TDT and DID see more leakage (though not bad). Going back to T6 dropped the leakage down again. I'm not a big believer in the 'synthetics cause leaks more than conventional' line anyway, and even less so with RT6.

 

[salv]

Running Mobil Super HM 10w30 with a Fram Ultra XG8A. Runs amazingly quiet and smooth. I have some of the typical 4.0 leaks, but within a couple weeks time I stopped seeing drips of oil on the driveway. My leaks are no more than minor seeps. I poured all 6 quarts in last oil change because of the oversized filter, and I am still about a quarter quart overfull. Haven't lost any.