viscosity data 15w40 vs 5w40 ( in this test the 5w40 was actually a tiny bit thicker @ 100 °C...... )

SAE 15W-40

Temp.
[°C] Dyn. Viscosity
[mPa.s] Kin. Viscosity
[mm²/s] Density
[g/cm³]
0 1328.0 1489.4 0.8916
10 582.95 658.60 0.8851
20 287.23 326.87 0.8787
30 155.31 178.01 0.8725
40 91.057 105.10 0.8663
50 57.172 66.464 0.8602
60 38.071 44.585 0.8539
70 26.576 31.350 0.8477
80 19.358 23.006 0.8414
90 14.588 17.467 0.8352
100 11.316 13.648 0.8291


SAE 5W-40

Temp.
[°C] Dyn. Viscosity
[mPa.s] Kin. Viscosity
[mm²/s] Density
[g/cm³]
0 753.52 868.78 0.8674
10 378.65 439.85 0.8609
20 206.89 242.10 0.8545
30 121.90 143.70 0.8483
40 76.551 90.903 0.8421
50 50.861 60.849 0.8358
60 35.409 42.685 0.8295
70 25.631 31.135 0.8232
80 19.181 23.478 0.8170
90 14.742 18.185 0.8106
100 11.619 14.443 0.8045

If you want thicker go 5w50 !

So again I ask, why would you ever want to go to any higher weight xW-40 than you have too when even the 5W is 60-65 times the viscosity at 0C(vs 120x for the 15W) and 10x the viscosity at 40C(vs 13x).

They are pretty close at 30C, and even closer at 40C which is summer starting conditions in my eyes. My jeep is usually around 25C in the morning here in Utah since it drops down to the 50's pretty much every night.

_________________
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

I don't want to go any thicker but it's seem like a trend for many CRD owner here.

I'm not trying to be mean with you but, their is no such thing as oil " WEIGHT " the API rating is a viscosity grade and the " W " stand for " WINTER " . The oil weight is part of the multi-grade oil mith........ and even most mechanics can't even explain oil viscosity grade properly.

Ok - several misconceptions here, let me try to clear them up again:

Yes, the xxW-40 refers to "winter" oil rating, but that is only what the oil is when it is below 32 degrees F or 0 deg C. Freezing.
Once the engine is started and the oil / engine warm to above the freezing point, then the oil viscosity changes to a 40 weight because of the presence of friction modifiers within the oil itself.

Think of it like this: You have a glass of water that is water-thin. That is the "winter weight" and it pours very easily. Now you dump in a bunch of "friction modifiers" of balled up napkins or paper towels. Now how easily does the "much thicker" water pour? That is what oil in your engine does.

You WANT it to be thicker at higher temperatures. That is what protects the engine. The oil pump isn't the problem, and it can overcome the thickness issue as long as the base oil is not too heavy for the temperature. That is how they get those zero-weight oils, they use a MUCH THINNER base stock, and just add a lot more friction modifiers to the oil. But since you are now relying on something added to the oil... If that has to work harder (because there is a 40 point spread between 0 and 40) than with other base oils that are a bit thicker... Perhaps the modifiers get used up over time and the oil slowly gets thinner and less protective? If your base oil is thinner, then you have less of a safety margin if your oil change is longer than the lifespan of your friction modifiers.

This is why people in hotter climates (South Africa, Austrailia, etc) are suggested by the owners manual to use 15w-40. At above-freezing, yes, they are all still 40 weight oils. BUT, there are less friction modifiers in a 15w-40, because it only has to raise the base oil 25 points instead of 40 points like with the 0-weight base stock!

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the " W " in 15w40 mean winter !!!!! so read it 15winter 40. and again their is no such thing as oil "weight"

I think we need a sticky here


What's written on your oil bottle, and what does it mean?

This post may seem like going back to basics but I'm constantly surprised by the number of people who do not know, or understand, what is written on a bottle of oil, and therefore have no idea what they are buying/using.

To be blunt about the subject, if a bottle of oil does not contain the following basic information then DO NOT buy it! Look for something that does!

1) The purpose for which it is intended (i.e. Motor oil, Gear oil etc)

2) The viscosity (i.e. 10w40, 5w30 etc for Motor oils and 80w90, 75w90, etc for Gear oils)

3) The specifications that it meets (should contain both API and ACEA ratings)

4) The OEM Approvals that it carries and the codes (i.e. MB229.3, VW503.00, BMW LL01 etc)

Ignore the marketing blurb on the label - in many cases it's meaningless and I'll explain later what statements you should treat with some scepticism.

So, what does the above information mean and why is it important?

THE BASICS

All oils are intended for an application and in general are not interchangeable. You would not for example put an Automatic Transmission Oil or a Gear Oil in your engine! It's important to know what the oil's intended purpose is.

VISCOSITY

Most oils on the shelves today are "Multigrades", which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)

Multigrades were first developed some 50 years ago to avoid the old routine of using a thinner oil in winter and a thicker oil in summer.

In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature. The lower the "W" number the better the oil's cold temperature/cold start performance.

The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100°C. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number, the thinner the oil: a 30 oil is thinner than a 40 oil at 100°C etc. Your handbook will specify whether a 30, 40 or 50 etc is required.

SPECIFICATIONS

Specifications are important as these indicate the performance of the oil and whether they have met or passed the latest tests, or whether the formulation is effectively obsolete or out of date. There are two specifications that you should look for on any oil bottle and these are API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d'Automobiles) all good oils should contain both of these, and an understanding of what they mean is important.

API

This is the more basic as it is split (for passenger cars) into two catagories. S = Petrol and C = Diesel, most oils carry both petrol (S) and diesel (C) specifications.

The following table shows how up to date the specifications the oil are:

PETROL

SG - Introduced 1989 - has much more active dispersant to combat black sludge.

SH - Introduced 1993 - has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability.

SJ - Introduced 1996 - has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limits

SL - Introduced 2001 - all new engine tests reflective of modern engine designs meeting current emissions standards

SM - Introduced November 2004 - improved oxidation resistance, deposit protection and wear protection, also better low temperature performance over the life of the oil compared to previous categories.

Note:

All specifications prior to SL are now obsolete and, although suitable for some older vehicles, are more than 10 years old, and do not provide the same level of performance or protection as the more up to date SL and SM specifications.

DIESEL

CD - Introduced 1955 - international standard for turbo diesel engine oils for many years, uses single cylinder test engine only

CE - Introduced 1984 - improved control of oil consumption, oil thickening, piston deposits and wear, uses additional multi cylinder test engines

CF4 - Introduced 1990 - further improvements in control of oil consumption and piston deposits, uses low emission test engine

CF - Introduced 1994 - modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engines

CF2 - Introduced 1994 - defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engines

CG4 - Introduced 1994 - development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine tests

CH4 - Introduced 1998 - development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuels

CI4 Introduced 2002 - developed to meet 2004 emission standards, may be used where EGR ( exhaust gas recirculation ) systems are fitted and with fuel containing up to 0.5 % sulphur. May be used where API CD, CE, CF4, CG4 and CH4 oils are specified.

Note:

All specifications prior to CH4 are now obsolete and, although suitable for some older vehicles, are more than 10 years old and do not provide the same level of performance or protection as the more up to date CH4 & CI4 specifications.

If you want a better more up to date oil specification then look for SL, SM, CH4, CI4

ACEA

This is the European equivalent of API (US) and is more specific in what the performance of the oil actually is. A = Petrol, B = Diesel and C = Catalyst compatible or low SAPS (Sulphated Ash, Phosphorus and Sulphur).

Unlike API the ACEA specs are split into performance/application catagories as follows:

A1 Fuel economy petrol
A2 Standard performance level (now obsolete)
A3 High performance and/or extended drain
A4 Reserved for future use in certain direct injection engines
A5 Combines A1 fuel economy with A3 performance

B1 Fuel economy diesel
B2 Standard performance level (now obsolete)
B3 High performance and/or extended drain
B4 For direct injection car diesel engines
B5 Combines B1 fuel economy with B3/B4 performance

C1-04 Petrol and light duty Diesel engines, based on A5/B5-04 low SAPS, two way catalyst compatible.
C2-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible.
C3-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible, higher performance levels due to higher HTHS.

Note: SAPS = Sulphated Ash, Phosphorous and Sulphur.

Put simply, A3/B3, A5/B5 and C3 oils are the better quality, stay in grade performance oils.

APPROVALS

Many oils mention various OEM's on the bottle, the most common in the UK being VW, MB or BMW but do not be misled into thinking that you are buying a top oil because of this.

Oil Companies send their oils to OEM's for approval however some older specs are easily achieved and can be done so with the cheapest of mineral oils. Newer specifications are always more up to date and better quality/performance than the older ones.

Some of the older OEM specifications are listed here and depending on the performance level of your car are best ignored if you are looking for a quality high performance oil:

VW - 500.00, 501.00 and 505.00

Later specs like 503, 504, 506 and 507 are better performing more up to date oils

MB - 229.1

Later specs like 229.3 and 229.5 are better performing more up to date oils.

BMW - LL98

Later specs like LL01 and LL04 are better performing more up to date oils.


FINALLY

Above is the most accurate guidance I can give without going into too much depth however there is one final piece of advice regarding the labelling.

Certain statements are made that are meaningless and just marketing blurb, here are a few to avoid!

Recommended for use where.....
May be used where the following specifications apply.....
Approved by...........(but with no qualification)
Recommended/Approved by (some famous person, these endorsements are paid for)
Racing/Track formula (but with no supporting evidence)
Also be wary of statements like "synthetic blend" if you are looking for a fully synthetic oil as this will merely be a semi-synthetic.

Like everything in life, you get what you pay for and the cheaper the oil the cheaper the ingredients and lower the performance levels.

- By Simon from the Porsche 968 website.

Changing your oil and your oil filter are necessary to keep your car's engine running well.

Other characteristics of oil include film thickness and film strength.

I think the numbers you posted above really tell the story.
At 0 C, 15w40 is more viscous than 5w40.
Then as the oils warm up they both become about the same viscosity.

_________________
U.S. Army Retired

I wasnt singling you out, sorry if thats how it came across. What I meant was, why would anyone use a 10W or 15W over a 5W.

I dont think I ever thought the W stood for weight, I just have always used the term heavier or lighter weight oil to refer to its viscosity. A 15W-40 is a higher weight oil than a 5W-40 at low temps the same as a 5W-30 is a higher weight than a 5W-20 is at high temps.

_________________
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

I was reading back some of your post geordi and I have a hard time to understand how it's coming from the self proclamed "traveling mechanic for these engines" !!!!!

this post doesn't make any sense at all, first every 0w40 oil ( wish is a pretty new grade of oil ) will be at least rated " CF " don't you think ??? and for the availlability , here in Canada you can find Mobil 1 0w40 in any Whalmart .
And you don't seem to understand ( or belive......) API multi-grade viscosity oil !!!!
If the soot " clog the oil " like you said !!!!!! it should make it thicker no ?????

Your post on that tread are PURE speculation !!!!!!!!!!!!!!!!

I will try to answer your comments, but it is really hard to translate what you are intending to say because of the lack of complete sentences.

0w-40 may or may not be a "new" grade of oil, but not every oil has been certified by the API (American Petroleum Institute) as both a gasoline and diesel rated oil. Just because something has a particular grade does NOT make it suitable for every engine that calls only for that grade. You have to also look at the certifications and specifications.

In Canada you say you can find 0w-40 in every Wal-Mart. I'm sure you can, and also in every Canadian Tire. That is CANADA. Once you come south into the USA, you will find that there is a range on the map where "winter" is not really such a big deal. Most of the USA lives in that range - And diesel-rated 0w-40 oils are just not sold normally, if at all.

Someone else quoted one of my posts and tried to explain like I (or whoever he was commenting toward) was a moron and did not understand that the "w" stands for WINTER. I know that very well, and I am quite familiar with the API service grades and how a multi-grade (not weight) oil works. I'm the one that has been advising people to look at the service grade and not just the oil viscosity when they are buying it.

When soot loads an oil, it may become thicker, but that is NOT the kind of thickness you want - because that soot is abrasive and you have just "thickened" the oil with millions of sharp and hard little diamonds that will increase the wear on the engine's most vital parts. You want an oil that can handle the soot properly, and keep it suspended and trapped so it cannot contact any engine parts.

I'm sorry for my poor english geordi , I'm a french Canadian ( Quebec )

you are right not every oil are certified API, some oil are rated ACEA wish are the rating for europe where our engine is made......turbo diesel are everywhere over there , we're not talking about the good ol' american V8 here!!!!

as a precision the viscosity grade are from SAE not API , I was wrong on that one !

For conclusion I would say use a SAE 0W40 rated " CF " or more recent certification for our little engine.
a higher API certification like CJ-4 doesn't translate to a better engine protection, it's more about DPF and EGR compatible low emission standard related .
If your looking for the maximum protection for your precious engine you should go with EURO oil like Motul, Elf or Liqui Moly with the more suitable ACEA rating for diesel oil.

But at the end of the day there is nothing wrong with the Mobil 1 0w40 !!!!

But stay away from the 15w40 !!!!! ( you might get away with it in Az )

Seb

I may be wrong but as far as I recall CF is not rated for EGR use. Could be OK if your EGR is disabled but maybe not the best for a stock vehicle.

Geordi touched on a good point about how multigrades work that I will reiterate. The viscosity modifiers do indeed breakdown and they breakdown more than the base stock so the further apart the two numbers are the more the top number suffers at end of life due to friction modifier breakdown. So pulling some numbers from my stupid for example purposes, an oil that is rated as 15W40 may break down to be equivalent of a 15W35 at end of life whereas a 0W40 will lose more from that top number and may break down to be equivalent of a 0W30. Now, out of choice, which would you rather have in your vehicle?

Given your climate I'd agree that 0W40 is definitely the best choice for you in winter and is the best choice year round if you don't want to be bothered changing it seasonally. If you live somewhere that's warm year round it's maybe not such a bad idea to select an oil that is more appropriate for your climate?

The endless "oil" debate keeps recycling. It would be helpful to actually consult the API diesel oil "codes" at http://www.api.org/products-and-service ... tab_diesel and consider a bit of history. I won't go back to the days of "single" weight (sorry if you don't like that term and yes I know it's really viscosity) oils but suffice it to say today's multi-grade oils have long since made obsolete the need to change oil for "summer" vs "winter" driving. As a practical matter the difference between 0W-40 and 5W-40 is minimal at best and only matters during extremely cold starting as both oils perform as 40W at operating temperatures. 15W-X is another matter.

IMHO one needs to focus on a) reasonable oil change intervals based on you driving conditions (I favor 6,000 miles); b) a new quality oil filter at every change (yep way back when many companies said change filter every other time); and c) pay VERY close attention of API (not sure about across the pond) ratings. Here is where DCJ used cut and paste once too often as the CRD Owner's Manual says use synthetic (good) API Category CF or better (misleading at best). CF is a 1994 rating for diesel engines using high sulfur fuel. In fact CF rated oil is NOT legal or at least definitely not recommend for use in the CRD having been superseded by CG-4 required for engines meeting the 1994 emissions standards; CH-4 for those meeting 1998 standards; CI-4 for those meeting the 2004 standards. Bottom line is the recommended CF standard was over 10 years out of date when the 05/06 CRDs were being sold and the proper oil rating that should have been in the Owner's Manual at that time was CI-4. Ideally one should use a full synthetic 0W-40 or 5W-40, your choice, rated as CI-4 or the more recent CJ-4 although the older CH-4 might? be ok.

_________________
Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Vote to make this a sticky...thanks for the details mate!

_________________
2006 CRD Jeep Liberty / Cherokee - Weeks Stage 1 & 2, GDE Eco Tune, Carter In-Tank Fuel Pump & Provent 200.

The CF rating when our diesels were sold was still a valid API rating. There is no law being broken by recommending that rating! That rating matched up to the euro ACEA rating C3, which is for a light duty high speed diesel. Which our API does not does not account for, they just have diesel oil the same as a high torque low speed diesel uses. Not always going to the newest rating is best when talk about the API ratings. There are additives that older ratings have that are removed in the newer ones because of emissions or emission systems. I can't logically say why some people have good or bad luck with these different oils. My experience with Mobil 1 0w40 has been totally positive for 163,000 miles roughly. I have no problem finding it at Walmart here in Michigan, and prefer it because I know it will circulate the fastest to the top end of the engine when cold. It is a diesel rated oil for light duty high speed engines, do not use in a heavy duty engine.

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

I guess it all comes down to whatever your local climate is then.
Im gonna continue using 5w40 year round. Might even switch to 15w40 for summer.
And if I ever have to go to Canada in the winter, I wont be driving.

_________________
U.S. Army Retired

I totally agree on the driving to Canada in the winter thing! I am sticking with the heavier weight oils (15W40 OR 20W50) which I believe provide MUCH better protection in our higher temperature climates in the deep south where first thing starting temperatures can be in the high 80's or 90's. at times...

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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

Might as well go with monograde then like Delvac 1340 !!!!!

thought my leak was diesel oil turns out to be front axle leaking and collecting diesel soot then drip! Am I only 10w40 user. I have a feeling it's perfectly fine in summer. Mobil one flows great anyways in cold. I wonder if thicker Mobil one like 15w 40 is really what this engine needs. Uses splash to lubricate many parts and Mobil one does this great, Rotella T I am not so sure!

Here's a question though. If the 0W40 is bad for CRD, why would Jeep recommend using it in the owner's manual?