What the numbers really mean!
Viscosity is a measure of a fluid's internal resistance to flow and may be thought of as a measure of fluid friction and of the oil's film strength to support a load.
The lower the viscosity number, the less load the oil can support at the bearing surface on the crankshaft. The higher the viscosity number, the better the load it can support.
Oil has to be thick enough to maintain separation of critical moving parts!

Sufficient HTHS viscosity is critical in preventing engine wear in the critical ring/liner interface area by maintaining a protective oil film between moving parts.
The new heavy-duty engine oil category is PC-11, PC-11 will be split into two categories one with HTHS viscosity less than 3.5 and one equal to or greater than 3.5. PC-11 oils with HTHS viscosity <3.5 would offer FE benefits but will be restricted to engines designed to run on lower HTHS viscosity oils. This will exclude older engines...
The higher the HTHS viscosity, the better the wear protection!

To each his own, I would not run a 0 weight oil in anything period! The numbers do not lie!!! It is simply not worth the risk, and giving up a little fuel milage to provide better engine protection in the long run by running a heavier weight oil is cheap insurance....

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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

You probably do not drive it hard..... the turbo must not ever get used.

I, on the other hand .....

I guess you're not afraid of all the sand blast media that is blasting at all the moving internal parts of our engines, created by soot in all diesels no matter if you own a Tune or not.

Hence the reason why I say that you must not be driving your CRD hard, the oil will last longer. If you baby the engine, your oil may last longer.

Extended oil change intervals have killed many good engines, it's a foolish gamble for those on the other hand who drive their vehicle hard.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

The Mobil 1 Euro formula 0-40 is one of the most commonly used oils in 2006 and older Mercedes Sprinters here in the US which are CRD's with turbos and EGR's. These engines routinely go over 300K miles without bearing or turbo issues and many of these vehicles are abused as they are commercial vehicles heavily loaded. 10,000 miles is the normal service interval with some people reporting going longer on their oil if they have the ASSYST feature. These engines have a 9.5 quart capacity.

I personally use T6 in my Jeep CRD because other recommendation to use a higher viscosity oil for the rockers. As far as the Euro 0-40 oil...from everything I have read, it is nearly identical to their turbo diesel oil and holds soot just fine.

I pull this camper and a 16' utility trailer with a compact tractor in the summer, so yes I baby it. Yes there is still soot in a Diesel engine, but after the tune it is much less. Before it was tuned the oil would be black right after you restarted the engine. Mobil 0w40 starts easier in the winter and when the oil is hot it is still a 40 weight oil. John Deere has a synthetic 0w40 for all of their heavy duty engines, so it must be heavy enough.

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long live the diesel
Greendieselengineering
Full torque Eco-tune
0w40 oil
Mostly stock
Diesel's are towing machines

With my experience, you will never convince me that the Mobil 1 0w40 was a bad choice.
Before trading off my CRD, I had gotten 175,000 trouble free miles using Mobil1 0w40 with 6,000 mile oil change intervals.
Getting rid of the soot, by installing a GDE tune early in my CRD's life was the key.

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TWO Identical 2005 Liberty Sport CRDS
#1 CRD, 174,000 miles. Eco tune, Samco hoses. Mobil1 0-40w used since day one
#2 CRD 143,000 miles. Bought used (unknown history) with 100,000 miles. Samco hoses.
Eco tune, new rockers, and 5 volt glow plugs installed at 124,000 miles

I think some folks here are a little misguided about oil viscosity !!!! I also don't think there isn't any proof that the Mobil 0w40 is to blame in the supposed rocker issue.

At running temperature it should be no viscosity difference between 0w40 and 15w40 so no additionnal protection , for a cold start it's another story .........

Here"s an article about oil viscosity

From Driven Racing Oil

Viscosity is the most important property of a lubricant. Understanding viscosity promotes the ability to reduce wear, improve fuel economy and make more horsepower.

For starters, in oil nomenclature, “W” does not stand for “Weight”. It stands for “Winter” and that is the key to understanding viscosity grades. A 10W-30 is a multi-grade (two viscosities) motor oil, and as the name implies, it meets more than one grade. Forty years ago there were winter grades for cold weather and summer grades for warmer weather. A typical winter grade was 10W. A typical summer grade was 30. These oils were straight grade oils. A 10W flows well in cold weather, to protect the engine at start up, but it’s is too thin for use in the summer. A 30 grade grade oil, thick enough to protect in the heat, was recommended for summer use.

Then, multi-grade oils were formulated. A 10W-30 had the winter cold start flow properties of a 10W and the summer, high temperature thickness of a 30 grade. Multi-grade oils could stay as close to the optimum viscosity over a range of temperatures - not too thick when it is cold and not too thin when it is hot.

The difference between a 0W-30 and a 10W-30 is indicated by how well each flows at lower temperatures. The viscosity of hot oil is measured using different test parameters than when the oil is cold, so the numbers after the “W” don’t relate to the numbers in front of the “W”. The difference between 10W-30 and a 10W-40 is the high temperature viscosity. Obviously, a 10W-40 is thicker than a 10W-30 at high temperature.

Armed with knowledge of viscosity grades, how can we put it to good use? Remember that using oil with a viscosity that is too high can result in excessive oil temperature and increased drag. Using an oil with a low viscosity can lead to excessive metal to metal contact between moving parts. Using the correct viscosity oil eases starting, reduces friction and slows wear.

For even more effective start up protection, use a synthetic 10W-40 instead of a conventional 20W-50. The synthetic 10W-40 flows easily and still maintains enough viscosity to protect piston skirts and bearings when it gets hot. The improved temperature stability of synthetics make them a better choice for race engines and serious high performance engines. Even with a synthetic, however, viscosity changes with temperature. Selecting the correct viscosity for an application requires knowing the operating temperature of the oil. Engines that run high operating oil temperatures require higher viscosity oil.

Engines that run low oil temps require lower viscosity oil. Look at an NHRA Pro Stock engine, a NASCAR Sprint Cup engine and a World of Outlaws 410 Sprint engine. Each engine has a very different operating oil temperature – Pro Stock, 100°F; NASCAR, 220°F and sprint cars, 300°F. All three engines run very different viscosity oils as well − SAE 0W-5, SAE 5W-20 and SAE 15W-50.

Here’s another thought regarding viscosity. It is vitally important to keep internal engine clearances in mind. Looser clearances in the engine and oil pump require higher viscosity oil to maintain oil pressure. Tighter clearances need lower viscosity oil, which provides better cooling and improved horsepower.

Probably the most important part of that article:



So, what exactly are the main/rod bearing clearances of a factory new engine?
If both a 0w40 and a 5w40 are deemed acceptable by the manufacturer, which of the two oils will better fill those clearances?

And last but not least, as those bearings wear, which oil will continue to fill the increased clearances?

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U.S. Army Retired

The two have the same viscosity grade at operating temperature which is 40 !!!!

the only difference is the 5w40 will take a little longer to reach the head of the engine because it's a little thicker at cold temp. so it might take a little longer before the cams and rockers get proper lubrication.

But I don't think that's necessarily true, I was under the impression that oil pumps were constant displacement so it will pump the same volume regardless. Only once it hits the pressure at which the bypass valve opens will it flow less as some of the oil will just recirculate back. The 5W will hit this pressure first but that's why we don't floor our cars the second we start them.

Also, I thought that generally a 0W would be lower viscosity at operating temps than a 5W of the same brand/type. Its not hugely less and is still considered a 40 weight, but still less.

I don't disagree with you though, I would rather use a 0W vs a 5 or 10W as long as all the same benefits applied. Since the oil is always going to be substantially more viscous at startup, I don't see why 0w wouldn't always be the best option.

That said I would still rather put a purpose built diesel oil in my Jeep. Soot is one factor, but direct injection causes a bit of fuel dilution too. Being that basically ever diesel is DI at this point, I would bet the oils are meant to handle this. My F150 ecoboost(directed injected) had tons of blow by when I first bought it and draining the oil practically made my eyes water. It was not resolved until I rerouted the PCV system and put on a catch can.

Sent from my Nexus 6 using Tapatalk

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

Wow I love how oil discussions become so heated and technical...

For me it came down to what was available in my area I could easily pick up at Wall-Mart, NAPA,Tractor Supply or any decent auto parts store. I became a member here when I was just looking at getting a CRD. I read and asked questions and I still do. My oil of choice was Rotella T6 5w40. It's easy to get and was one of the more recommended oils on here back in 2009. others guy claimed to like were Mobile 1 turbo diesel truck and the Mobile 1 0w40 which in my area was not available so much and not the diesel rated one. From just over 37,000 mile to now somewhere over 115,000 I been using T6, changing it before the EVIC counts down the 6,250 miles between changes and for about the last 3 or 4 years getting a sample to Blackstone labs at least once a year. My lab test have always been good. I tow a camper a few times in the summer and often a utility trailer, carry kayaks and bikes, use the Jeep as a daily driver for a 20 to 30 minute commute of mixed city and rural 2 lane roads, also my normal driving includes some highway.

Reading this is the 1st time I ever heard someone say shorter change intervals than 5000 miles were a good idea, based on my blackstone labs reports I'm not so sure I'd agree with that at least for my driving anyway others my fit that.

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2006 Liberty CRD Limited Deep Beryl Green Metallic Clear coat, Fumoto valve, MH ProVent (removed), GDE Eco tune,
OME 790/948 springs, OME struts, OME N132L shocks, Jeepin by Al A-arms, Hercules Terra Trac AT2 245/75R16
Weeks Stage 1 EGR delete, 5 volt steel glow plugs

I jump back and forth between Rotella T6 and Mobil1 TDT. I just get whichever one is on sale, usually I order a whole bunch when the price is good. Right now I am sitting on 3 Gallons of M1 TDT which I am working though and then there is another 6 Gallons of T6 I snagged at a good price.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

Mobil 1 0w40 is a great oil and though not an approved oil for my new ride, a Santa Fe with the 2.0 turbo, it is what I will use with 5,000 mile oil change intervals (90% highway driving at 75-85 mph). I like it because it is a PAO oil and flows great on starts.

However, I won't use 0w40 oil in my CRD unless it is a true diesel rated oil spec and if someone does use it, I wouldn't go past 3k oil change intervals due to soot loading.

I always chuckle at stories on forums regarding diesels that have soot free oil at high mile intervals. With 3 diesels in my stables and having owned another half dozen diesels over the past 15 years, all of my diesels turned the oil black in 500 miles. This includes diesels that were tuned including my KJ CRD and WK CRD.

I'm happy that there are reports of folks hitting over 100k miles on 0w40. I have 161,500 as of today and am on original turbo, lifters and rockers. I was going to replace my turbo, rockers/lifters as preventative maintenance with the intent of keeping my WK CRD another 150k miles but 10 years is the longest I've ever owned a vehicle and I had to scratch the itch for a new daily commuter.

I will say that my 2.0T Santa Fe is pretty nice. It has a 3,500 lb tow rating and I've gotten 28mpg by laying off the boost. 264 horsepower at 6000 rpm and 269 lb-ft of torque at 1,750 rpm is acceptable. However, I likethe the WK CRDs 185 HP and 335 lb-ft torque better; its not as high strung. On a side note, Hyundai Forums are quite lacking in the knowledge base found here and other diesel related forums.

Mobil1 0w40 is a diesel rated oil. "Europe uses a more intelligent rating system for oil." That being said by one of my dealerships past service representatives. ACEA oil rating and use is based on engine mechanical design, emission systems, and viscosity requirements. I really don't care what oil anyone else is using.

_________________
long live the diesel
Greendieselengineering
Full torque Eco-tune
0w40 oil
Mostly stock
Diesel's are towing machines

Yes, GTDI motors are pretty sweet. At this point, if there is an option between GTDI and Diesel in anything besides a commuter car or 1ton pickup, I would probably go GTDI.

I know what you mean on the lack of knowledge. I think the less unique and/or performance focused your car is, the less knowledgable people there are around. The Jeep CRD's are a good example, Pontiac GTO forum I was on was great resource, Trailblazer SS forums. When you start getting onto places like the F150 forums you get a lot of people that dont know a brake caliper from a windshield wiper. There are knowledgeable people, but they make up a much smaller %.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

My apologies for repeating inaccurate information.

Turns out Mobil 1 0w40 is

Rated ACEA A3/B4: Stable, stay-in-grade oil intended for use in high performance gasoline and direct injection diesel engines, but also suitable for applications described under A3/B3.

It is also ACEA A3/B3: ACEA A3/B3 Stable, stay-in-grade oil intended for use in high performance gasoline engines and car & light van diesel engines and/or for extended drain intervals where specified by the engine manufacturer, and/or for year-round use of low viscosity oils, and/or for severe operating conditions as defined by the engine manufacturer.

So, where did the idea that Mobil 1 0w40 can't suspend soot as well as other heavier weight diesel oils come from?

Another option is Mobil Delvac 1 ESP 5W-40

https://mobildelvac.com/en/engine-oils/ ... lvac-1-esp

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There is also a Mobile 1 Delvac ESP 0w-40.
But I think it's only available in Canada.

Compare the specs of the Delvac ESP 0w-40 and the regular Mobil 1 0w-40.
They are different but I don't know what it all means.

And I'm pretty sure that the Delvac ESP 5w-40 is the same as Mobile 1 turbo diesel truck 5w-40.

_________________
U.S. Army Retired

The Mobil 1 Delvac ESP 0w-40 is availlable in Canada ( on sale @ Canadian Tire right now !!! )

I think it's a good choice for our engine too. from what they say about it , it looks like a more commercial or industrial diesel oil blend to meet the spec of some engine builder.


Mobil Delvac 1 ESP 0W-40 meets or exceeds the following industry and builder specifications: 0W-40
API CJ-4/CI-4 PLUS/CI-4/CH-4/SM
Caterpillar ECF-3
Cummins CES 20081, 20076
Mack EO-N Premium Plus 03

on special for 37.95$ cnd a jug it might end up being my next oil change !!!

The Mobil 1 ESP oils are designed for use in diesels with DPF systems, they are described as low SAPS and are supposed to help prevent clogging of the DPF. As for Mobil 1 0w40, it's approved for diesel use, but as Mobil 1 Turbo Diesel 0w40 is readily available, it tends to be the preferred oil over here.

My visit with Keith at GDE, I learned that these engines can call for up to a 15W40 in hot weather climate uses in other markets. I use 15W40 in summer use only (except this summer, as I am laid off and the Jeep is sitting with a broken TC or Flexplate). In my opinion, the Amsoil Full SAPS is the way to go, and comes in 5W40 and 0W40 weights (I use the 5W40). Keith uses Rotella T6 in the 2 Rams and the CRD, and doesn't have an issue.

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2006 Sport, GDE FT Eco Tune, Custom Trans Tune
2015 Ram 1500 Big Horn EcoDiesel, GDE Hot Tune