Same here, without the rotella.

 

This

 

Good thread, but there are some myths here.

The 4.0 is a flat tappet engine, yes, but it DOES NOT need ZDDP. Here is why...


The newest 4.0 (2006) is 8 years old, and they have been running a majority if not their entire lives on passenger car motor oil without lots of ZDDP. The reason they are fine, is that while the 4.0 is a flat tappet design, it has very low valve spring pressures. A brand new engine that has not been broken in, or a performance engine such as a stroker with high tension valve springs would benefit from higher ZDDP oils such as Rotella. A stock engine will be fine on almost any oil of the correct grade.

The 4.0 engine is unlike the muscle cars with flat tappet engines and higher tension valve springs. Those engines DO benefit from higher ZDDP oils, and without them you have cases of wiped cam lobes like in your pics. The difference is in the spring tension and the amount of pressure the valvetrain puts on the cam.


Rotella is a great oil, and I wouldn't hesitate to run it in a 4.0 engine. I run it in many of my diesel equipment applications as well as outdoor power equipment with great success. I would not say the 4.0 engine NEEDS Rotella though, which seems to be the info found in this thread.

I have done 2 UOAs on Pennzoil Yellow Bottle conventional oil. One was 5w30 and the other was 10w30. The 10w30 returned single digit iron wear numbers, some of the lowest I have seen among 4.0 UOAs.

Bottom line, the 4.0 will do well on any oil of the correct weight. As long as the oil is changed, it will live a long healthy life. People will actually do more damage to their engine running a 15w40 diesel oil in a cold environment than they will running a modern 5w30. Change the oil and it will be fine.

Here is a link to my UOAs:

http://www.bobistheoilguy.com/forums...OA#Post3256885


I'm not hating on your thread. Lots of great info here and I appreciate the time and research that is obvious from your findings. I just want to add some info on what I have found about the 4.0L.

 

Good info. This is what I referred to earlier, instead of bashing, post up findings and tech research to contribute. Thanks for your findings.

 

Good information! And you're absolutely right, the 4.0 doesn't need Rotella, it'll run well on any oil of the correct weight, they're so tough you could probably run tiger blood in it!

 

Much truth here. This is what I've been saying, but so far it has fallen on deaf ears.

 

Nice post!

This has been a learning experience for me discovering how engine parts interact and how lubricants really work. I understand your comparison against muscle cars with very high spring pressures but I don't don't quite agree with your premise that the 4.0 "DOES NOT need ZDDP". The 4.0L definitely needs anti-wear additives, and ZDDP is one of those additives. It doesn't necessarily need ZDDP specifically but something's got to be present. Your UOA looks awesome (especially for a winter sample) and I totally completely agree that Pennzoil Yellow Bottle is a great 30-weight conventional oil. It's got pretty good qualities just on the oil side (I suspect that 10w30 has a good HTHS like 3.3 or higher, which would make it acceptably close to the ACEA A3 standard) and a good dose of modern AW additives. (Not to mention that PYB comes on sale for a pretty good price ) However saying that the 4.0 "DOES NOT need ZDDP" might lend one to think that oil like Castrol GTX is a good idea, when a quick glimpse at the facts reveals it pales in comparison to even Walmart's SuperTech.

What I set out to accomplish when I started this thread is to establish WHY so many people think Rotella is the best, and I think I've identified that. The topic of discussion not "what is good enough?". Plenty of oils are of excellent quality and I wouldn't hesitate to recommend a lot of the oils I've reviewed here. Your engine obviously isn't going to explode, but it isn't necessarily going to last as long as it might on another oil either. This is exactly why I am not really interested in the 2006 4.0Ls. Yes they've been running for a period of time on SL, SM, and now SN oils without incident, but, like you wrote, these engines are only eight years old and in Jeep terms are barely broken in. I am more interested in a 20-year old engine with 200-300k on it. Although honestly around here everything rusts apart long before this is a concern.

I totally agree with you regarding running 15W40 during winter. This is a huge no-no if the engine isn't near an acceptable operating temperature.

During my research I stumbled across a thread on the Jeep Strokers comparing average numbers from UOAs between people running xW30s and xW40s. The post showed similar iron numbers, but slightly elevated bearing wear from xW40s. The guy had the right idea, but because he grouped results from 0W40 all the way through 15W40 made it pretty much useless. The difference across the range at cold startup is so vast that I could not include such a huge generalization.

But yeah absolutely 15W40 when the world is ice and snow is not good for longevity.

 

I saw that Jeep strokers thread and thought the same thing. Comparing an Xw30 to all Xw40s kind of blurs the line. A 5w30 to a 5w40 might be a better comparison, but like you said a 15w40 will yield different results compared to a 0w40 or 5w40 in colder temps. A lot of it also depends on how the Jeep is used. A Jeep running 5w30 during the winter that is being used as a commuter vehicle will have different wear than one using 5w30 crawling rocks in the desert. I have had good results with 10w30 Pennzoil, but if I was crawling in Moab during the hot summer you can bet I'd be running Rotella T6.

As far as my statement "4.0s do not NEED ZDDP" I should have clarified. I meant that they do not need ZDDP specifically. An anti-wear additive is definitely important. Like you mentioned, I have seen several UOAs done on Castrol that have not come back the greatest, and the worst I've seen have been with Mobil 1. For whatever reason, Mobil 1 (regular, not high mileage) causes the 4.0 to shed even more iron. Pennzoil conventional contains a good amount of molybdenum as an anti-wear additive, which is probably why it has yielded great results in my application.

Thanks for taking the time to do the research for this thread, there are many threads on various forums about "so and so ran brand X so that is the best".

 

Interesting about Mobil1 and iron. I recall reading something similar and was quite surprised.

Yeah the giant slug of moly in PYB makes it a pretty nifty oil. I'd consider running it if I didn't have 15L of T6 in my shed lol. I've recently acquired a TDI that basically requires the stuff so... eh...

 

Anyone notice an increase in lifter/valve noise after switching to Rotella T6? Just changed my oil today(was synpower 5w-30), and there seems to be an increase in chatter.

 

When I switched from 10w30 conventional to the to tell T6 I actually noticed a decrease in valve and lifter noise. Guess everyone's rig is different though!

 

My engine's noises stayed the same from Mobil 1 5w30 to Rotella T6 5w40.

Any change in your oil pressure? Reliable filter?

 

My oil pressure went up about 8- 10psi and I was running Bosch, none purolator classic

 

Using same brand filter (Napa Gold), didnt notice any change in oil pressure. Maybe i'll give it a few days.

 

I've had the best iron readings with M1 HM (compared to GTX HM and Royal Purple.) I have regular M1 5w30 in right now, might do another analysis and see if the non-HM didn't do as well.