On the M-1 0W-40 weight, I have heard anecdotes from two users with OM603 turbo engines. On the one engine, hydraulic lifter noise started to appear. Switching back to M-1 15W-50 cured the noise. On the other engine, oil analysis showed noticable increased iron wear in PPM with the 0W-40, which again dropped back to "normal" with either M-1 15W-50 *or* Delvac-1. This is purely anecdotal, and wasn't first hand, so take it with a grain of salt. My opinion is that the 0W-40 is great for squeaking that last iota of MPG out of an engine, but for better wear/longevity, I'd prefer the 15W-50 or the D-1. And I can't see *any* advantage to the 0W-40 other than another 1% MPG, unless you live at the North or South Pole...!!!

;)

Thats exactly right. If an engine is designed with tolerances such that it needs a 15wt oil for proper lubrication cushioning, etc., you will see increased wear at normal tempoeratures, due to the low startup viscosity (where the cushioning of a thick oil is most necessary).

Lifter noise with 0w-40 seems odd, pressure should build faster, and thus fill the lifters faster. But I guess diesels have more force on the valves or something, so the heavy thick oil that isnt as easily displaced is necessary...

I have seen jeep I6 engines that 'suggest' 5w-30 do really great on 0w-40, and Ive seen BMW (and now MB) engines that 'suggest' 15w-40 or 20w-50 do average or poorly on the 0w-40.

I think the 0w-40 is a great oil MAYBE in cars with older engines using 5w-30, or in cars designed for it. But cars that typically want 15wt oils, and arent starting at THAT cold of temps, will just have less protection on the wear areas that ought to have the thick 15wt.

JMH

JHZR2,

Got the data from Mobil by email. Interesting how you get differing info from from the same company. Still not very much differnce when comparing 5200 and 7000 centipoise at -20C., but it is a differnce. This maybe the result of slightly different formulations. Also, 7000cp @ -20C. is the minimum standard for a 15W, and that may have been what I was quoted. All 15W's will be relatively close regardless of whether or not they are dino or synthetic. If there was a significant difference it wouldn't be marketed as a 15W.

I don't particularly care for large range multigrades. More viscosity modifiers end up as deposits inside the combustion chamber and they tend to shear down more. Mobil 0W-40 and 15W-50 are large range and do tend to shear down despite being synthetic. If you are going to spend the money for synthetic, Delvac 1 is much more shear stable over longer intervals due to very little viscosity improvers.

Rotella Synthetic 5W-40 does have slightly better CCS specs than Delvac 1, but after a few thousand miles on the oil the pour point depressants will be less effective and it will thicken. This is the weakness of the group III synthetics.

I do like your idea of mixing Delvac 1 and Delvac 1300. Was that a 50/50 mix? Did you do an UOA?

Okie, I think I understand where youre coming from... But you have to look at thge big picture.

there is a HUGE difference between a 15wt synthetic and a 15wt dino oil at cold temperatures. (and in disagreement to your previous post, the difference between 5200 and 7000cP at -20 is giant!) If we consider the specs for a 15wt oil, we know that the cold cranking viscosity must be a maximum of 7000cP at -20C. Similarly, we know that a 20wt is 9500 at -15and a 10wt is 7000 at -25. If it is less than 7000cP at -20, it may retest at the next coldertemperature to see if it slides under the maximum viscosity for that one as well (you had posted that this is the minimum viscosity at some temperature, which is wrong; if it was the minimum, then all oils thicker than 7000cP at -20 would be eligible for 15w- status, and so molasses would qualify for a 15wt oil, just as m1 would).

The thing is, that with a dino oil, it will be significantly thicker at 5C colder test temperatures. A synthetic fluid will remain nearly the same at 5C colder, thus the rason why they can meet a viscosity grade at say, -15, yet still pour at -54C. They may or may not qualiy for the next lower viscosity, that is a function of the oil's viscosity index.

In other words, you know that the CCS test is used to determine the low number, at the different temps shown above. However, this tests tells you nothing about how the oil is going to work when you get down BELOW the CCS temp. So a 5w-30 petroleum oil will start to thicken rapidly below -25C and have a higher pour point than a 10w-30 synthetic. For extremely cold weather, the more relevant number is the borderline pumping temp, or BPT. This defines the practical low temp limit of the lubricant - when you get down to the pour point, the oil is going to be too thick to pump out of the crankcase. The synth will pump at far lower temperatures than the dino oil, and similarly, the pumping viscosity of a dino vs a synthetic, say, 15wt at -20C will be vastly different, and in this regard, the synth oil will pump and move far better in the engine at the same temperature, as compared to the dino oil.


Now, regarding the viscosity spreads... Synthetic oils often contain NO Viscosity index improvers. Lets first talk about how a lube oil is made, as dino and synth oils are made in completely opposite methods.

In the case of a mineral oil, you start out with a base oil of 15wt(15w40 for example). You then add some VII to enhance it to the 40wt as it heats up. So you start out with a low molecular basestock and add VII's to span the temperature range of operation.

In blends, the addition of small amounts of PAO's and esters help the base stock's stability and increase the VI without the addition of high concentration of VII's.

In the case of a real full synth, for high quality true synth bases (Group IV, V), the original VI of one oil, or a mixture of various synthetic stocks with different viscosity indices will be so high that you may not need VII's. Start with a base oil of 40 weight. With the natural flow properties of full synth's (which are the reason for the benefits), you can measure using the cold cranking simulator for example, to say what a 20 weight oil would flow. If the oil will provide the same basic cP(centipoise)reading of what a 15 weight oil, then it can be classified as a 15w40, even though it doesn't use any VI improvers in this formula.

Take this same oil, 40 weight, re run the same CCS test, and now test the flow to what a 5 weight oil does, if it meets that spec, it now can be labeled as a 5w40 even though it is being used as a 15 weight in the previous example. Again, with no VI improvers. Some small lube oil companies actually use this sort of a basestock oil, so that they can improve the prices of their oils by only having one synthetic oil. It technically meets the viscosity standards for many grades, and so can be used.


The viscosity index improvers are quite important issues when considering dino oils. To make a typical 10w-30 oil:
VI Improver to Achieve 10W30 Grade
Group I 10%
Group II 5%
Group II+ 3%
Group III 1%
Group IV 0%

If you go the way of dinos, you use a particular additive package focused on the shortcomings of dino; AW, detergent/dispersants, VII's, anti-foam, etc.

For full PAO/ester synthetics, you only need mix in the additives you to beef up the AW qualities, detergent/dispersants, anti-foam, etc.

And,one can come to the conclusion that a good barrier lubrication (moly is a good example) is more important in low temp start conditions, so long as the weight of the oil is appropriate for the temp. This is regardless of the dino/synth debate, since after many hours, little to no oil will be on the engine parts, and only the antiwear package of the oil will be there to protect the parts that are subject to friction.

So this is why, technically, synthetics are still superior to dino oils. This doesnt mean at all that MB diesel engines dont last, or last any less with a dino oil. They may, depending upon conditions and oil weight, crank easier with the synthetic oil as compared to the dino oil. But, as I stated in your previous oil thread, the real reason for going with synthetics is their inherent ability to be used for extended drains, increasing their economy, as well as improved fuel economy, oil induced drag (that naturally is a sink of a few hp), etc.

I hope this proves to be informative to everyone. I am not trying to start another flame battle or anything, I am just stating the facts as I know them from my own study.

JMH

JMH - many thanks for the excellent writeup. I agree 100% and you write much more eloquently on this topic than I do. :D :D

Thanks!

Ill admit I spend way too much reading up on this stuff when I ought to be doing schoolwork and research :D

JMH

Okie,

regarding the UOA for the 50/50 mix, I found the results rather ordinary. I found similar ordinary results within a few ppm when using straight delvac 5w-40. Typically in the 617 engine I see about 15-20ppm per 3000mi.
But timing chain stretch can be avoided by using synthetics, and that is not correlatable to Fe UOA numbers. But, plenty of timing chains have gome probably 400k on dino oil and 3k intervals.

I actually like the rotella 5w-40 oil, when sold at a price point of a GIII oil ($13/gal or so). Makes a nice oil for lawnmowers, etc., I have found, because it does have pretty strong properties in its additive package, etc., and doesnt burn up as easily as regular dino oils, in older riding mower engines that are a bit tired. I tried it in my truck, but it seemed to bog it down, despite the 4.3L chevy v6 being an old design, probably originally made to use 20w-50 or straight 30wt oil... Although Im thinking the 'bogged down' feel may be something else, and I might try it again in there. I liek the strong additive package of this diesel oil, since that truck sits a lot, and the good price, since Id probably change it every half year at 3000mi and wouldnt be wasting as much money as with M1. But I believe you with regards to the shearing out of grade. The thing is, it shouldnt shear out too much, and if I have a high end 30wt, Im happy... Thanks for reminding me to rethink the rotella synth use in my truck :)

JMH

I recently switched to 0W-40 in my 82 300D and it starts a lot easier at below-freezing temps than it did with dino 15W-40. Why do you say MB engines that suggest this viscosity do poorly on 0W-40? I'm sure I now have a lot less cold-start wear thanks to the 0W-40. Sure it's a little thinner at high temps, but not much. BTW, the originally recommended oil for our cars is 10W-40, not 15W-40 which is recommended only for temps above 23F.

I stated this evidence from the info given by gsxr of the OM603 engines develloping valve lifter noise. I do not have UOA to back it up, but all things considered,if youre having easy starts with 15w-50, and changing to 0w-40 does nothing by make noise, the 15w- is probably a better oil for your piece of mind (although the GM 4.3 and other engines can have valve ticking at startup for the same reason, for 100k miles and still be running like day 1).

Thus my statement.

Have you figured what is the burn rate of this oil? I am curious about this for my own usage, I just wonder about big tolerances on a cold engine being protected with a thin oil. Granted, by 40C, the oil is pretty thick, speaking volumes about the quality of this oil.

BTW, the typical profile of the M1 0w-40 oil from UOAs that Ive seen is that itll start out at a 40 wt, and in 5k or so miles, it will have sheared down to a slightly thinner 30wt oil. As time goes by, it will actually re-thicken slightly, so it does indeed stay in grade over a length of 10k miles or so (a requirement for the mb 229.x series specs).

JMH

Why go from 15W-40 dino to 0W-40 synthetic? You bypassed the 15W-50 synthetic, which IMO provides better protection for older MB engines, with almost no loss in cold start performance. Remember that 15W-xx dino and 15W-xx synthetic ARE NOT the same viscosity in sub-freezing temps...!

I recently had another thread about this called "Is 15W-40 too thick for below-freezing temps?". Anyway, I didn't bypass 15W-50, in fact I almost bought it. At the same time my 82 300D was having a hard time starting in cold weather with dino 15W-40 and I was afraid the M1 15W-50 wouldn't help, since it's even thicker than 15W-40 at 40C and I assume the same is true at lower temps except at extremely low temps like -30C which don't concern me. I would like to see a viscosity comparison of these oils at 10F - 20F or so.

As far as oil consumption goes, I switched to 0W-40 about 2 weeks ago and don't have any results on that yet.

40C is like 120F... Thats an indication of a partially warmed engine in regular (not cold service) situations. Its thicker at 120 because of the 50wt viscosity... Nothing wrong with that. Since the viscosity at 100C will be higher for a 50wt oil, it of course needs to be hgher at 40C typically, as well.

Remember, Cold cranking and pumpability are the important factors in sub freezing temps (and pour poiunt is a function of these factors, so is a quick and dirty first-order approximation of the cold temp performance, although at the pour point, the oil wouldnt protect your engine... Its certainly the edge of the envelope).

Not that Im saying that there is anything wrong with your 0w-40 choice. It is at least as thick as a 10wt oil at 40C, and flows a whole lot better when freezing cold. But as I expressed before, since most of these engines are designed for 10 or 15w- oils, I just worry about a bit of burning as the thinner stuff slips through the seals at more temperate or situations where the engine has partially cooled. Thats why I was interested. And if MB reccomends 0w-40 for your engine, use it in full confidence regardless, so long as its within the temp range :)

JMH

The 0W-40 and 15W-50 variations of Mobil-1 should have very, very little difference in pourability down to at least zero F (that's -18C). Like I keep saying, unless you live in truly Arctic climates with temps in the -40 range or colder, the M-1 15W-50 should provide almost the same starting capability as teh 0W-40 with (arguably) increased high temp protection.

Like I said before, put a quart of each in your freezer and see for yourself!

I SWITCHED TO MOBIL 1 0 40 ABOUT 3000 MILES AGO . I REALLY LIKE THE IMPROVEMENT in the coldweather starting . it dropped it 15degrees. the car started at - 36f 2 weeks ago. that was with the block heater and the oil heater on . but the bad is the car has used 3 qts of oil in that time which is not normal with regular rotella oh yea it an 83 300tdt with 248k miles. just my experience.
i am going to 15- 50 at 5000 miles to see if that stops the oil use.
JOHN M

JHZR2, rest assured that I know what 40C is. I grew up using Celsius and can convert between F and C in my head accurately. What I was saying is that I was only able to find the relevant oil viscosities at 40C and 100C on Mobil's website. I wish they had data for 0C or -10C or something like that, as that is (like you seem to imply) more relevant than 40C. Even better, how about a curve showing viscosity vs. temperature? That'd be nice. :) IMO, pour point doesn't tell you much as I don't think viscosity and temperature have a linear relationship.

I'm gonna keep an eye on my oil consumption. I might also try the 15W-50 in my two other cars. Right now they're still running on Delo 400.

Gsxr, I did do the freezer test a while ago, but I don't think the results are easy to interpret and they're unreliable. True, my 0W-40 seemed quite thick too, not much different from 15W-40, but my car certainly starts easier with it.