Which oil to use for my Jeep 4.0?

Status
Not open for further replies.
Joined
Sep 30, 2013
Messages
16,183
Location
Indiana
Yet another 4.0 oil thread.. I want her to get a good daily dose of zddp.

Yes there are many threads about this subject, but I am a firm believer that the 4.0 is a very unique engine and not all of them act and sound the same way.

Ive been running M1 5w40 TDT synthetic for about the last 50x miles in my engine which has 150x total. Its a 2003. About 15x miles ago, she developed a slight lifter tick. These engines are notorious for it. It would come and go, but be more noticeable on cold Indiana start ups. I would normally just let it warm up like a diesel truck and it would be good to go so I lived with it. Due to availably, I had to use 10w30 M1 HM. (I believe I had stated in another thread I used 5w30 HM, but I found the bottle today.. it was 10w oil.) And well what do you know, the tick has almost gone away. It is present for a few moments on startup, but that's about it. While most people think the 4.0 needs a thick HDEO, I feel mine likes the thinner stuff.

Questions:

Is the thinner oil quieting down my lifters or is it just in my head? Maybe the HM flavor has different detergents than the TDT? My instinct tells me it would have less than the TDT only because diesels are pretty dirty.

Ive read multiple places that the M1 HM oil contains ether (seal conditioners or " seal swellers") Would that create an issue on my RMS? I actually called M1 and the "technician" said most of their oils already contain seal conditioners. But this was also the guy who recommended I ran 5w 50 synthetic oil.. I saw a 550+ horse mustang at a car show that wanted that stuff. I doubt that's what my jeep needs.. haha

How about the European 0w40 M1? I just worry the oil wont stick to the internals properly. or just be plain too thin. I checked the M1 site and the viscosity, cSt (ASTM D445) @ 40 degrees Celsius is 75 for the 0W40 the 10w30 HM is 78.1 @ 40 degrees Celsius. Not too sure on what those numbers mean exactly, but the 0w40 almost seems a tad bit thinner.

Or should I just drop M1 all together and find something else? Id like to stay on synthetic. There is also the RT5 which is the 10w30 synthetic blend. Im a little hesitant about the blend part.. Id rather it be full synthetic. And plus it also says on the back on the bottle that its compared to RT 5w40 oil so it sounds like its just like the M1 TDT. I want to stay on a thinner oil.

Im currently running the M1 filter as well, but im planning on going to Wix next oil drain.

Thanks
 
Think of the 4.0 as a tractor engine in a Jeep. Not that picky.

All synthetic oil contains seal conditioners, the HM stuff normally has seal swellers (not for me).

If you can get by the cracked head and piston skirt issues, its a good engine.
 
Originally Posted By: Donald

All synthetic oil contains seal conditioners, the HM stuff normally has seal swellers (not for me).



I guess I didn't know there was a difference between a seal conditioner and seal sweller.
 
I plan on doing one on this oil. Still have about 3500 miles to go.

Like you said, don't fix something that isn't broken. Why condition a RMS when it doesn't leak. Thats my worry.
 
Originally Posted By: Donald
Think of the 4.0 as a tractor engine in a Jeep. Not that picky.

All synthetic oil contains seal conditioners, the HM stuff normally has seal swellers (not for me).

If you can get by the cracked head and piston skirt issues, its a good engine.


you can get by the piston skirt failure and "0331" casting by not buying 99-01.....

Dont worry the other 50 years they made that motor does not have that issue !
crazy.gif
 
Originally Posted By: dlundblad
Yet another 4.0 oil thread.. I want her to get a good daily dose of zddp.

Yes there are many threads about this subject, but I am a firm believer that the 4.0 is a very unique engine and not all of them act and sound the same way.

Ive been running M1 5w40 TDT synthetic for about the last 50x miles in my engine which has 150x total. Its a 2003. About 15x miles ago, she developed a slight lifter tick. These engines are notorious for it. It would come and go, but be more noticeable on cold Indiana start ups. I would normally just let it warm up like a diesel truck and it would be good to go so I lived with it. Due to availably, I had to use 10w30 M1 HM. (I believe I had stated in another thread I used 5w30 HM, but I found the bottle today.. it was 10w oil.) And well what do you know, the tick has almost gone away. It is present for a few moments on startup, but that's about it. While most people think the 4.0 needs a thick HDEO, I feel mine likes the thinner stuff.

Questions:

Is the thinner oil quieting down my lifters or is it just in my head? Maybe the HM flavor has different detergents than the TDT? My instinct tells me it would have less than the TDT only because diesels are pretty dirty.

Ive read multiple places that the M1 HM oil contains ether (seal conditioners or " seal swellers") Would that create an issue on my RMS? I actually called M1 and the "technician" said most of their oils already contain seal conditioners. But this was also the guy who recommended I ran 5w 50 synthetic oil.. I saw a 550+ horse mustang at a car show that wanted that stuff. I doubt that's what my jeep needs.. haha

How about the European 0w40 M1? I just worry the oil wont stick to the internals properly. or just be plain too thin. I checked the M1 site and the viscosity, cSt (ASTM D445) @ 40 degrees Celsius is 75 for the 0W40 the 10w30 HM is 78.1 @ 40 degrees Celsius. Not too sure on what those numbers mean exactly, but the 0w40 almost seems a tad bit thinner.

Or should I just drop M1 all together and find something else? Id like to stay on synthetic. There is also the RT5 which is the 10w30 synthetic blend. Im a little hesitant about the blend part.. Id rather it be full synthetic. And plus it also says on the back on the bottle that its compared to RT 5w40 oil so it sounds like its just like the M1 TDT. I want to stay on a thinner oil.

Im currently running the M1 filter as well, but im planning on going to Wix next oil drain.

Thanks


I go with T5 in my 4.0's (and there have been many) but use a 5-30 Pennzoil HM in the winter months. most guys run HDEO or M1 HM in there 4.0s it seems. IMO the perfect oil would be T5 in 5-30..... or 5-40. I'm not a M1 fan, based purely on price it just does not make sense IMO.

ALLOT of info here about 4.0's and oil, look around.
 
Originally Posted By: dlundblad
Originally Posted By: Donald

All synthetic oil contains seal conditioners, the HM stuff normally has seal swellers (not for me).



I guess I didn't know there was a difference between a seal conditioner and seal sweller.


PCMO does not have seal swellers in it, they have seal conditioners. It's the base oil that conditions the seals, group V esters, in particular. I learned that here from the resident tribologist.

Now brake fluid, that would be considered a seal sweller. An old transmission trick was to add a bit of brake fluid to the trans fluid to swell the seals on a worn out unit to make it perform better to get someone to buy it.
 
Your 4.0L does not require a daily dose of ZDDP. SM/SN rated oil has plenty for the factory low tension valve springs. I like the 5W30 SOPUS GrpIII synthetics, but if the TDT has been working well for 50K, why change?

I have always felt that 2.5/4.0/258 engines have only adequate valve train oiling and have repaired about a half dozen noisy lifter Jeeps with a HV Melling oil pump. In my experience, the factory oil pump life expectancy is about your mileage anyway, so you may want to look into it.
 
Been running HM oil in the '94 for the past 26K, ever since I got a large collection of the Pennzoil HM on clearance. It's RMS has never leaked (consider myself lucky). The HM stuff hasn't seem to have had a negative effect so far, but then again this is only 26K on the HM stuff. Don't think you'll have issues with yours though.

Were the '03 exhaust manifolds prone to cracking also? My '95 Cherokee had cracked manifold and it sounded like a lifter tick. Took a while to figure that one out.
 
Originally Posted By: gomes512
Been running HM oil in the '94 for the past 26K, ever since I got a large collection of the Pennzoil HM on clearance. It's RMS has never leaked (consider myself lucky). The HM stuff hasn't seem to have had a negative effect so far, but then again this is only 26K on the HM stuff. Don't think you'll have issues with yours though.

Were the '03 exhaust manifolds prone to cracking also? My '95 Cherokee had cracked manifold and it sounded like a lifter tick. Took a while to figure that one out.


I dont think its much of a problem in the WJ's, It's my understanding that the header/manifold failures in the XJ's was due to the motor mounts being worn or bad or possibly not upto par from the factory.
BUT I do have a stock 4.0 header for sale with built in flex joints !!
 
I've just learned to accept the noises my two 4.0s make. They never make the SAME noises, either. But they're indestructable- really don't worry about what oil you give it. If you want to try thinner, just try a passcar 5w30 like the Jeep manuals actually call for- M1, M1EP, PU, PP, PYB, PYP (pick yer poison).

There's nothing at all wrong with M1 0w40, either. Its about as stout as an HDEO, but it is a little thinner yet within the range of a 40-weight. Its got plenty of ZDDP for the lightweight valve springs a 4.0 has- I run M1 0w40 in my two 60s vintage 440 Magnum v8s with much stiffer valve springs- so no worries there either.
 
Originally Posted By: 440Magnum
I've just learned to accept the noises my two 4.0s make. They never make the SAME noises, either. But they're indestructable- really don't worry about what oil you give it. If you want to try thinner, just try a passcar 5w30 like the Jeep manuals actually call for- M1, M1EP, PU, PP, PYB, PYP (pick yer poison).

There's nothing at all wrong with M1 0w40, either. Its about as stout as an HDEO, but it is a little thinner yet within the range of a 40-weight. Its got plenty of ZDDP for the lightweight valve springs a 4.0 has- I run M1 0w40 in my two 60s vintage 440 Magnum v8s with much stiffer valve springs- so no worries there either.


My parents have had 3 4.0s and a 258 - my 2000 4.0 is quieter than all of their AMC Inline 6 engines.

Also the highest mileage.

Mine is chattery, but quieter than most 120K 4.0 engines.
 
Last edited:
Originally Posted By: Realtech214
Throw some delvac 15w40 in that thing, Cant beat the 12$ /gallon pricetag at wallymart


yeah !
wait till you here that at start-up when its 0 degrees out......
 
It can get pretty chilly in parts of Indiana, which is why I recommended the 0w40 / 5w40 synthetic. Will a 10w30/15w40 start in winter? Yes it will but Fe wear should be higher with the thick HDEO.
 
Realistically, PYB in the 5W30 flavor is all his 4.0L needs in winter. IMO, there is no need to run any XW40 unless you're snow wheeling and experience increased oil temps.

The 4.0L is a simple engine. No need to overthink the lube.
 
Originally Posted By: Zaedock
Realistically, PYB in the 5W30 flavor is all his 4.0L needs in winter. IMO, there is no need to run any XW40 unless you're snow wheeling and experience increased oil temps.

The 4.0L is a simple engine. No need to overthink the lube.


Who has a JEEP that don't play in the snow
33.gif
21.gif


YOU SHOULD BE ASHAMED OF YOURSELF !!!!!
spankme2.gif
 
Last edited:
Status
Not open for further replies.
Back
Top