Does this engine have flat tappets and require the extra ZDDP in a HDEO? I am using PP or PU currently.
2001 Jeep WJ with 4.0 engine
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Yes it does, I use a lot of Rotella in mine and it works very well, but I'm currently running Pennzoil for the winter and no discernible tick, in fact the quietest its ever been. I'm wondering if all the moly in PYB offsets some of the lack of ZDDP.
I have done a LOT of fiddling with mine, 2004 4.0, and mine doesn't like anything heavier than a 10w30. I'm not the only WJ owner to comment on this. Older 4.0's in XJ's and such seemed to thrive on even 40 weights. I mention this as I suggest you not fall into the 15w40 HDEO experiment, Rotella is readily available in 10w30 so I'd try that if you're going to go that route.
Mobil 1 High Mileage has higher ZDDP as well if synthetics are your preference, another popular choice for the 4.0.
I have done a LOT of fiddling with mine, 2004 4.0, and mine doesn't like anything heavier than a 10w30. I'm not the only WJ owner to comment on this. Older 4.0's in XJ's and such seemed to thrive on even 40 weights. I mention this as I suggest you not fall into the 15w40 HDEO experiment, Rotella is readily available in 10w30 so I'd try that if you're going to go that route.
Mobil 1 High Mileage has higher ZDDP as well if synthetics are your preference, another popular choice for the 4.0.
It does have flat tappets. The 4.0 has a pretty mild valvetrain setup, so it'll generally run fine on anything once it's broken in.
I run T6 5W-40 in my mom's 99 WJ 4.0, and a friend just switched his 01 WJ 4.0 from M1 5W-30 to T6, and both are running beautifully with minimal valvetrain noise, etc.
I run T6 5W-40 in my mom's 99 WJ 4.0, and a friend just switched his 01 WJ 4.0 from M1 5W-30 to T6, and both are running beautifully with minimal valvetrain noise, etc.
As already mentioned the 4.0 does have flat tappits. But the lowered zddp does not seem to hurt them any. I'm on several jeep forums and flat cams are rare. Maybe 2 or 3 threads a year.
I am also running the Pennzoil Yellow Bottle (recommended to me by KCJeep) with great results in my 2000 4.0L. The 4.0 does have flat tappets but it has mild valve spring tension so any passenger car motor oil will be fine. With a 4.0L, using a good quality filter like a Wix or Purolator seems most important. I ran Mobil 1 high mileage 10w30 in mine and it seemed louder and actually consumed oil, even though it never did in the past.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
Im running Mobil 1 0w-40 in mine and the jeep seems to be happy, great for cold starts and has boosted ZDDP levels the same as M1 HM oil and about the same as rotella
I have also run M1 tdt 5w-40 in mine in the summer and start of winter and I have no complaints there either, I just wanted to try 0w-40 for fun. lol
I may try Mobil 1 HM 5w-30 next fill since my RMS is leaking and i have fun trying new oils but i might put TDT back in. Im also tempted to try T6 for the fun of it too. 0w-40 will be my winter oil next year its just a bit expensive buying individual quarts for summer
I have also run M1 tdt 5w-40 in mine in the summer and start of winter and I have no complaints there either, I just wanted to try 0w-40 for fun. lol
I may try Mobil 1 HM 5w-30 next fill since my RMS is leaking and i have fun trying new oils but i might put TDT back in. Im also tempted to try T6 for the fun of it too. 0w-40 will be my winter oil next year its just a bit expensive buying individual quarts for summer
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Originally Posted By: jeepman3071
I am also running the Pennzoil Yellow Bottle (recommended to me by KCJeep) with great results in my 2000 4.0L. The 4.0 does have flat tappets but it has mild valve spring tension so any passenger car motor oil will be fine. With a 4.0L, using a good quality filter like a Wix or Purolator seems most important. I ran Mobil 1 high mileage 10w30 in mine and it seemed louder and actually consumed oil, even though it never did in the past.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
I am on engine #2 due to piston skirt damage. When it let go and jammed/seized the engine, the rod was no longer attached to the piston.
I am also running the Pennzoil Yellow Bottle (recommended to me by KCJeep) with great results in my 2000 4.0L. The 4.0 does have flat tappets but it has mild valve spring tension so any passenger car motor oil will be fine. With a 4.0L, using a good quality filter like a Wix or Purolator seems most important. I ran Mobil 1 high mileage 10w30 in mine and it seemed louder and actually consumed oil, even though it never did in the past.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
I am on engine #2 due to piston skirt damage. When it let go and jammed/seized the engine, the rod was no longer attached to the piston.
IMO, I wouldn't worry about having a oil with extra ZDDP in it. With the spring rates being mild, and many of these 4.0's running 200K+ miles with no problems with the valve train on plain old dino oil.
I'd just stick with the 10W30 oil and filter combo that your running now.
I'd just stick with the 10W30 oil and filter combo that your running now.
As others have said, given the mildness of the valvetrain, not really an issue with the ZDDP levels of modern motor oils if you are past the break in stage. Beyond that, these are one of the least picky engines for motor oil. Keep it topped off, and that's about it. I run the cheapest name brand dino 5w30 in the winter time, 10w30 in the summer time, with no issues on my '88 Cherokee with the 4.0.
Originally Posted By: Donald
Originally Posted By: jeepman3071
I am also running the Pennzoil Yellow Bottle (recommended to me by KCJeep) with great results in my 2000 4.0L. The 4.0 does have flat tappets but it has mild valve spring tension so any passenger car motor oil will be fine. With a 4.0L, using a good quality filter like a Wix or Purolator seems most important. I ran Mobil 1 high mileage 10w30 in mine and it seemed louder and actually consumed oil, even though it never did in the past.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
I am on engine #2 due to piston skirt damage. When it let go and jammed/seized the engine, the rod was no longer attached to the piston.
Did you find out what caused the piston damage? I have seen a '96 and a '98 4.0L with broken piston skirts. They were able to pop a new piston in and run it before the engine locked up.
Originally Posted By: jeepman3071
I am also running the Pennzoil Yellow Bottle (recommended to me by KCJeep) with great results in my 2000 4.0L. The 4.0 does have flat tappets but it has mild valve spring tension so any passenger car motor oil will be fine. With a 4.0L, using a good quality filter like a Wix or Purolator seems most important. I ran Mobil 1 high mileage 10w30 in mine and it seemed louder and actually consumed oil, even though it never did in the past.
If it were me I'd run a good Dino oil like PYB 10w30 and use a good quality filter (like a Wix) and keep the oil changed.
That jeep also has the 0331 head casting which is more prone to cracking, especially after an overheat. Not all of them will crack, but its important to keep an eye on your coolant level. A "mysterious loss of coolant" and milkshake looking oil are the common symptoms.
I am on engine #2 due to piston skirt damage. When it let go and jammed/seized the engine, the rod was no longer attached to the piston.
Did you find out what caused the piston damage? I have seen a '96 and a '98 4.0L with broken piston skirts. They were able to pop a new piston in and run it before the engine locked up.
Originally Posted By: jeepman3071
Did you find out what caused the piston damage? I have seen a '96 and a '98 4.0L with broken piston skirts.
Pretty common problem with the 2000 and up engines.
Did you find out what caused the piston damage? I have seen a '96 and a '98 4.0L with broken piston skirts.
Pretty common problem with the 2000 and up engines.
I had 3 grand cherokees in the past, and had great results with valvoline maxlife 10w30. made the engine smooth or at least smoother than with other oils.
Originally Posted By: aztec12
I had 3 grand cherokees in the past, and had great results with valvoline maxlife 10w30. made the engine smooth or at least smoother than with other oils.
I don't doubt it, Maxlife used to be loaded with moly, it's not anymore unfortunately but PYB is and seems to create the same good results.
I did score some moly loaded SM Maxlife a couple weeks ago cheap though LOL!
I had 3 grand cherokees in the past, and had great results with valvoline maxlife 10w30. made the engine smooth or at least smoother than with other oils.
I don't doubt it, Maxlife used to be loaded with moly, it's not anymore unfortunately but PYB is and seems to create the same good results.
I did score some moly loaded SM Maxlife a couple weeks ago cheap though LOL!
Originally Posted By: Chris142
Pretty common problem with the 2000 and up engines.
I doubt it is common with 2000 and up engines. What is your statement based on? More of them have issues with the 0331 head cracking than piston issues.
Pretty common problem with the 2000 and up engines.
I doubt it is common with 2000 and up engines. What is your statement based on? More of them have issues with the 0331 head cracking than piston issues.
i hear about all these problems 4.0s have and then Im told they are super tough and reliable, which is it? Im sick of hearing both!
To me you can't have a tough legendary engine if they are all cracking or failing in one way or another. It sounds like a few people have had problems and word spread and now we all panic about it, just like the OCOD craze here, a few had failed and now everyone acts like they are all horrible and will explode just because they read that one guy on the internet brother's son's jeep broke.
lol i Never know what to think about the 4.o jeep
To me you can't have a tough legendary engine if they are all cracking or failing in one way or another. It sounds like a few people have had problems and word spread and now we all panic about it, just like the OCOD craze here, a few had failed and now everyone acts like they are all horrible and will explode just because they read that one guy on the internet brother's son's jeep broke.
lol i Never know what to think about the 4.o jeep
Originally Posted By: MrRPM
i hear about all these problems 4.0s have and then Im told they are super tough and reliable, which is it? Im sick of hearing both!
To me you can't have a tough legendary engine if they are all cracking or failing in one way or another. It sounds like a few people have had problems and word spread and now we all panic about it, just like the OCOD craze here, a few had failed and now everyone acts like they are all horrible and will explode just because they read that one guy on the internet brother's son's jeep broke.
lol i Never know what to think about the 4.o jeep
The 4.0L has had the same basic design its whole life. A few things were changed here and there mostly for emissions reasons. In 1999, they switched to a different head casting (0331) which had smaller exhaust ports to heat up the cat converters faster. This helped the ancient engine pass new emissions standards. Unfortunately there was a flaw in the new casting and some of the heads on '99-'02 4.0Ls can crack. Not all of them will for sure, but some do, especially from neglect. This is the only issue I am aware of that can impact some 4.0s. Most of them are very well built and long lasting. I've seen a few of these "crack prone" 4.0s running around with 250k+ with all original engine stuff.
i hear about all these problems 4.0s have and then Im told they are super tough and reliable, which is it? Im sick of hearing both!
To me you can't have a tough legendary engine if they are all cracking or failing in one way or another. It sounds like a few people have had problems and word spread and now we all panic about it, just like the OCOD craze here, a few had failed and now everyone acts like they are all horrible and will explode just because they read that one guy on the internet brother's son's jeep broke.
lol i Never know what to think about the 4.o jeep
The 4.0L has had the same basic design its whole life. A few things were changed here and there mostly for emissions reasons. In 1999, they switched to a different head casting (0331) which had smaller exhaust ports to heat up the cat converters faster. This helped the ancient engine pass new emissions standards. Unfortunately there was a flaw in the new casting and some of the heads on '99-'02 4.0Ls can crack. Not all of them will for sure, but some do, especially from neglect. This is the only issue I am aware of that can impact some 4.0s. Most of them are very well built and long lasting. I've seen a few of these "crack prone" 4.0s running around with 250k+ with all original engine stuff.
right, i know what the problem is, i have a 2001 so i keep my eyes peeled and am always checking over things to make sure it hasn't happened. Next to that i hear about piston skirt failure (but have only seen 1 real case here it appears, haven't seen it anywhere else, just "heard" about it.) I have also seen tons of oil pump drive gears stripping out on 05/06 wranglers on the web. People are always talking about common problems that can cause failure of the engines. That to me says they aren't the reliable tractor engines they are made out to be. Im also thinking maybe i just spend alot of time online where people go to discuss the problems and I see it alot and feel like its over discussed lol
The 4.0's reputation is well deserved in my opinion and experience. A couple design tweaks late in it's life tarnished it's otherwise spectacular record.
The 99-01 WJ's and TJ's can have the piston skirt issue, and the 00-01 XJ's some of those had the bad heads. Even many of those are plugging along without major repair well over 200k, and the other years of the 4.0 are 300-400+k engines. Try that with a 4.7!
Just saw a guy the other day post he had 384k on his 02 WJ, and was finally gonna rebuild it because it was just plain worn out and the power wasn't there anymore. It was still running fine!
The 99-01 WJ's and TJ's can have the piston skirt issue, and the 00-01 XJ's some of those had the bad heads. Even many of those are plugging along without major repair well over 200k, and the other years of the 4.0 are 300-400+k engines. Try that with a 4.7!
Just saw a guy the other day post he had 384k on his 02 WJ, and was finally gonna rebuild it because it was just plain worn out and the power wasn't there anymore. It was still running fine!
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