1998 Grand Cherokee 4.0

[onus]

I have no clue what weight oil this takes. My guess is 10w30. Is this correct? Anyone know the sump capacity off hand? What should i run for oci. Like 5k? It does 90% highway.

This is my mom's jeep. She doesn't know when the oil was last changed. Her ex used to change the oil.

Leaks oil like crazy ( well not too bad but noticeable ). In the summer I'm Going to put a new pan gasket, and rear main seal on. Seems to be a common problem on these jeep's.

Where can i get oil change reminder stickers since i wont be driving it and surly wont remember the mileage.

 

[bigjl]

In the UK these are run on anything from 5w30 to 10w40, normally to 7/8k.

Your idea of 5k sounds pretty sound, easy to remember if you can start to do it on the tens and fives like I do on the Pathfinder.

I am sure a Jeep fan will be along to give a better recommendation though I suspect I would use Mobil 1 New Life 0w40.

A very good oil at a decent price.

Though with your oil leaks why not look at Valvolene NextGen Maxlife, some really good offers have been posted up on the forum of late.

Good enough for me to consider getting it sent to wife's brother in NY then shipped to the UK.

 

[tstep]

I had a 94 4.0 GC oil burner. It burned alot of oil. If memory serves it was 6 quarts of 10w30. In my situation, it was a combination of burning and leaking. As bad as all that was, the engine was still running @ 265k miles when I quit driving it. I think the heads were prone to cracking in some of the 4.0 engines. Worth checking it out.

 

[bigjl]

The '98 is the squarer shape Grand Cherokee isn't it?

Always liked them even though they are completely impractical for the UK and tend to be driven (in the UK) by the kind of driver that thinks a service is topping the oil up and adding water.

They are so cheap they have be one throwaway.

Mainly due to the fuel consumption.

 

[71Chevyguy]

The 4.0 inline 6 engine holds 6 quarts of oil.

The factory recommended oil is 10w30.

Any 5w30 would be fine as well especially in the cold weather we have now in most parts of the country.

I would suggest 0W30 as well but if you say it is leaking then a synthetic oil can make your problems worse. I would suggest a high mileage oil regardless of the mileage on the Jeep. It may not fix your problem but it may slow down your oil leak so it is worth a try. Many suggest Valvoline MaxLife oil which has proven itself to be a good oil. I do not personally feel that those engines are that picky with oil as long as it is changed and kept clean you should be fine.

Interval? Hard to say, if the oil in there is black then I would personally not go past 3k just to clean it out. If the oil has been in there a long time and is not very dirty then 5K is probably fine with a decent name brand oil since you say it is mostly highway driven. A diesel oil such as Rotella T5 10w30 is probably fine in it too, would clean it up some with the detergents the diesel oil has. I have heard of many using Rotella T6 5w40 in those engines as well with good success.

 

[Astro14]

Any of the parts stores will give you free oil change stickers if you buy something else there...so, I would look for a special on oil, and pick up a few stickers while you're at it...

By the way, it's 6 QTS of 10W30 specified...so, you can safely use a 5W30, or even a 0W30, if you like...my recommendation is to buy what's on sale in a 5W30 or 10W30...

 

[greg_J35]

Some report good analysis using Rotella T or T5 10w30. Either with a purolator filter should by fine. As for stickers, Advance Auto Parts has them.

 

[KCJeep]

The factory spec is 10w30, capacity should be 6 quarts. The manual lists 5w30 as acceptable during cold temperatures, but it was written nearly 15 model years ago. I'd not be too concerned about 5w30 today, but the Jeep 4.0 is well known for favoring oils on the thick side. No need for overkill though. I prefer thick 5w30's like Castrol High Mileage for mine, which is thicker than most run of the mill 10w30's, or to blend standard 5w30 with 10w40 50/50 to get a thicker 30 grade oil with a much higher VI than most 10w30's.

Rotella 10w30 is also a popular favorite for the 4.0. Maxlife is another good choice and I've had really good results with Pennzoil conventional as well.

That said the 4.0 would probably run 100k on used cooking oil so no need to overthink it.

 

[bullwinkle]

I had a 50/50 mix of 15W40 Rotella & Valvoline NextGen MaxLife 10W30 in my '98 4.0 Cherokee, actually seemed a little noisy, so I drained (sump only, not filter) the oil & put in MaxLife full synthetic 5W30-it got a LOT quieter, got a keeper! The owner's manual states 10W30 preferred, 5W30 below 32F, people run everything from 0W30 to 15W40 in the 4.0 with good results. Mine is now at 211K, I changed the leaky valve cover gasket & cracked PCV grommets about a month ago & the top of the head was close to spotless, ZERO blowby! Now if I could just do something about the gas mileage...

 

[bigjl]

As you seem to be knowledgeable on these vehicles could i run a question past you?

For future reference, in the unlikely event I end up with one in Ghana, due to import taxes not any issue with the vehicle I might add.

What do you think about running Mobil 1 New Life 0w40?

What about the later ones?

Do they use similar oils?

 

[bullwinkle]

Also, oil change stickers are available from most auto part stores for free, and I talked Mobil into sending me some in the past as well. If I were you-I would stick to silicone ADBV equipped filters (Purolator Pure One, Fram Ultra, Motorcraft FL-400S, Bosch Distance Plus-they look orange inside) because the sideways mounted filter has a tendency to allow the oil to drain back into the pan-ESPECIALLY if the Jeep sits an extended time without being used. 4.0s are noisy enough as it is!

 

[KCJeep]

Originally Posted By: bigjl
As you seem to be knowledgeable on these vehicles could i run a question past you?

For future reference, in the unlikely event I end up with one in Ghana, due to import taxes not any issue with the vehicle I might add.

What do you think about running Mobil 1 New Life 0w40?

What about the later ones?

Do they use similar oils?



The factory spec's remained unchanged throughout the remainder of of the engines production, which finally ended in the Wranglers in 2006.

For whatever reason, Jeep 4.0's have consistently produced extremely high iron used oil analysis when run on Mobil 1, meaning up to triple the iron most other oils produce, including the highly esteemed here Mobil 1 0w40. We could debate why until the cows come home, but it is simpler in my mind to just make a different oil choice since that syndrome does not seem to appear with any other oil brand other than Mobil 1.

Since you're in Europe I'd suggest a good thick Castrol brew for your Jeep.

 

[Kuato]

Originally Posted By: 71Chevyguy
The 4.0 inline 6 engine holds 6 quarts of oil.

The factory recommended oil is 10w30.

Any 5w30 would be fine as well especially in the cold weather we have now in most parts of the country.

I would suggest 0W30 as well ...


Agree 100%; we own one. Have been using 5w30 or 0w30 for several years with no leaks and no issues.

Once you get the pan gasket changed you should be fine; until then I'd use an inexpensive conventional to save on topping off.

I've done used oil analysis with SuperTech conventional and Valvoline, and both went 5000 miles and were still in good shape. With your 90% highway driving this would probably work well for your mom also....instead of a sticker, why not calculate how many miles she drives a week and then just mark the calendar? She might not even look at the sticker.

 

[Gabe]

Originally Posted By: KCJeep
[I'd suggest a good thick Castrol brew for your Jeep.


Quick question: Do you suggest a thick oil due to low oil pressure or are you predicting better wear numbers with a thicker oil??

 

[KCJeep]

Originally Posted By: Gabe
Originally Posted By: KCJeep
[I'd suggest a good thick Castrol brew for your Jeep.


Quick question: Do you suggest a thick oil due to low oil pressure or are you predicting better wear numbers with a thicker oil??


Neither actually, a detailed Jeeper on another forum did an exhaustive UOA study for the 4.0 and concluded there was virtually no wear difference in the 4.0 between 30 and 40 grade oils, other than aluminum (pistons) which was slightly (and I do mean slightly, just a couple ppm) lower with the 40's.

But keeping in mind the Jeep 4.0 originally dates back to the 60's, it's seems to "like" oils that run a little thicker. And when I refer to thicker, please don't misunderstand me I'm not referring to 10w40's or HDEO 15w40's (although a lot of Jeep guys prefer those) I'm referring to a "thickish" 30 grade. I actually pay more attention to HTHS and I like to start with an HTHS of 3.3 to 3.5 for mine, either by initial selection or blending to get there.

Just my preference, like I said it'd probably do 100k on used cooking oil.

I'm currently working on 3 consecutive used oil analysis on mine using progressively thicker oils of the exact same brand and type just to see what I end up with. Running a Castrol High Mileage 5w20/5w30 blend which equates to a standard 5w30 right now, that's the first run. Second run will be a thick 30 and the third a thinnish 40, but it will take me the better part of a year to get through all that ha ha.

 

[Donald]

I have one with a 4.0 and run 10W30 synthetic. I go about 7500 on Pennzoil Platinum or Pennzoil Ultra. Given that its your mom's vehicle and it might not get the maint. routine you would do for yourself, I would go for synthetic oil as its more forgiving if an OCI is extended or forgotten. At Walmart we are talking an extra ten spot for synthetic vs conventional. Well worth it even on a 1998.

 

[onus]

Thanks guys! I Definitely a fan of purlator filters. I ran motocraft on my 351w i have. Rebranded purlator iirc.

Right now the oil doesn't look to bad but i have added 4 quarts since a month or two ago. Freaking leaky thing.

Good tip on the calendar. If i put the sticker their my mom will remember to check it.

Good to know about the 30weight. Once i get my 7.3 idi to stop leaking i'm thinking of switching to amsoil 10w30 / 30 weight stuff they have. In that case i could use that it both of these.

I want to run synthetic. I totally agree with the maintenance thing. But with it being leaky it will just cost me more. When its fixed it will be the first thing i do.

 

[toneydoc]

I have the same engine in my Jeep and it is doing fine with minimal leakage. Has timing chain, no belt except serpentine, and is easy to work on and with. The owner manual states 10w30 unless you get below 0F degrees and then it recommends 5w30. However, this is almost a bulletproof engine and will last a long time if well maintained. It does not care what brand of oil you use in it as long as it is of good quality. Therefore buy what is on sale or FAR and change the gaskets like you stated and it should run a long time.

 

[SwampSurvivor]

If you want to go with a good, cheap synthetic, cna't go wrong with Rotella t6 (provided you want a 5w-xx for winter!).

But they aren't terribly picky. Mine seems to be happy with a mix of 5w-20 and 5w30 for winter.

 

[The_Jeff]

There's a sale on amazon on peak 10w40. What I'd run if it's pouring out the rear main seal.

Also check if the longer FL1a filter fits.