I'll be glad to discuss the rigors of metrology, it's what I did in my first two years at IBM, but don't want to bloviate.

You are correct that the first skill to master is learning to read the incremental capabilities of the device.

Next you need to determine if the increments are limited because that is the resolving ability (or accuracy and/or repeatability limitation) of the device or (such as in this case) in most instances it would both clutter and provide unnecessary information.

If the device is consistent, repeatable and resolvable then further resolution is warranted. If you publish using this data you would have to demonstrate that to be the case.

You make 10 measurements at 81 ēC, 10 at 82 ēC, etc. If the results warrant it you can than interpolate the device.

When I initially said I notice a 3 ēC to 4 ēC decrease using 5W-40, synthetic, that was a very modest claim, given the caliber of the gauges in these older MB.

But, you would never let a student do this until they had mastered the more basic skill.

BTW - a great example of being able, if competent, to improvise, interpolate and resolve was the make-shift adaptation is the use of sextant and measuring the diameter of the sun in the capsule window as the crippled Apollo 13 limped home. It was shown in Ron Howard's great movie and can be read about here -

http://history.nasa.gov/SP-350/ch-13-4.html

.

Great question.

... you are off in your calculations...
there are 20° between graduations, not 10...
where you have 82.5 would be 85
so it's at 90 where you have it marked 85
where you have it 87.5 would be 95

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Thanks. You are correct.

Double my numbers.

Still able to note the 3 ēC to 4 ēC difference I initially mentioned.

In my case it was actually pretty easy to notice the difference because previously there was a noticeable black space between the pointer and the 80 ēC mark.

After changing to the thinner synthetic the needle was centered in the 80 ēC mark.

And what I wanted to know was whether others had noticed a temperature change going from 10W-40 petro-based to 5W-40 synthetic?

That really is the question I'm still curious about.

Keep on letting me know when I make technical errors. Don't want to mis-inform.

This is the steady-state reading, on level ground of my current situation.


I had not taken a picture of the needle prior to the oil change.

If we take this reading, compare it to the next and imagine that the difference was twice as great, meaning that we could now see a black space between the needle and the 80 ēC mark then you'd have my situation.


Based upon actually taking a picture and laying out the rough reticle I estimate the difference in temperature for these two pictures to be ~2.5 ēC. But I would say 'it looks like just under 3 degrees to me."

Until empirical evidence would contradict I'm comfortable saying that my gauge can accurately resolve and measure a ~3 ēC difference. (in the 80 to 100 range).

However, it is only because the needle is in the vicinity of the 80 degree tick mark that I can observe this while driving. If the needle is in the intermediate area, between ticks, it would require either exceptional visual acuity or photographs to do so.

And where do you think that the ethylene comes from???? Oh, that's right, from cat crackers breaking down CRUDE, and from natural gas reformers... Both contain all that big, bad sulfur and other junk... surprise, surprise.

Slack wax (its not just any crude that makes grp III stocks) or cat cracker offgas? hmmm, not much difference. Both are BYPRODUCTS of other petrochemical processing.

You can build a molecule up, or you can chop one down. If you hydrotreat and fundamentally change the atomic structure, you still get the right end product.

Any there is plenty of research that has found that grp IV needs adds to do everything that other stocks do. Oxidation resistance, which is a key one, is superior with grp III.

How about you head over to bobistheoilguy and start doing some detailed reading rather than spewing half-truths? Oh and by the way, it was never fought about the basestocks AT LAW. It was a better business bureau case.



For the rest of the crowd, if I was shopping purely on the basis of pour point, because I was heading to the arctic, I'd consider grp IV/V (both of which are blended with other basestocks because they have their own issues). If Im looking for the best overall performance, that would be only one of my considerations for circumstances where it matters. There certainly is a good basis to have some grp IV/V blended in so that its benefits can be balanced with the benefits of the other basestocks and additives. Please keep in mind that the additive package is as important as the basestock in determining how well the oil protects and performs, AND, the add pack can be as expensive as the base oil! To choose an oil based upon some preconceived "value proposition" is silly and short-sighted.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

JHZR2

w124 diesel, turbo

Ambient temperatures between 40 to 100 F, most around 60 to 80 F.

Sea-level to 400 feet. modest hills.

Please advise which oil you would use.

Thanks.

Same, mobil1 5w-40 year round.

Crude oil fields? Oh, it doesn't? Crap.

False.

False. Its base is still crude oil.

That is false too.

Please do, though your poorly informed rants are quite entertaining.

If they can provide empirical evidence of repeatability and accuracy it is acceptable.

That would consist of making 25 measurements or so and then repeating the process half-a-dozen times, at various times under various conditions.

It is improbable (but could occur) that their interpolations will be acceptable.

In many ways it comes down to is the procedure appropriate for a wide-range of applications, people, situations or are we dealing with a craftsman, an artisan, who has mastered their discipline and can take their tools to the edge of their abilities.

That's what I have done with the MB temp gauge, only because I asked about temperature changes due to different oils.

PS - I'm not making any claims about myself being in the category master craftsman, etc. I have my skills but few of them are in the dominant areas covered on this board.

Ya, M1 is a good product and has probably some of the best protection available. But even Rotella T6 is wayyyy better then what was available in 1989 when that engine was new.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

What is entertaining is your pretense that you know something about this area when all you can do is make unsubstantiated claims with nothing to back it up.

We can go into peer-reviewed literature if you like... Youve probably never even looked at a technical journal article.

OK, where shall we start? Ethylene?

"Ethylene is produced commercially by the steam cracking of a wide range of hydrocarbon feedstocks. In Europe and Asia, ethylene is obtained mainly from cracking naphtha, gasoil and condensates with the coproduction of propylene, C4 olefins and aromatics (pyrolysis gasoline). The cracking of ethane and propane, primarily carried out in the US, Canada and the Middle East, has the advantage that it only produces ethylene and propylene, making the plants cheaper to construct and less complicated to operate."

http://www.icis.com/v2/chemicals/9075778/ethylene/process.html

Hmmm.. wonder where naphtha and propane feedstocks come from. Maybe they are magically synthesized from carbon and hydrogen at the chemical plant? Please. Dont be so naive. Again, build molecules up or crack them down and isomerize them until they are the same structure, you still get the compound.

Now, group III basestocks...

"A modern Group III oil can actually outperform a PAO in several areas important to lubricants, such as additive solubility, lubricity and antiwear performance. Group III base oils can now rival PAO stocks in pour point, viscosity index and oxidation stability performance."

http://www.machinerylubrication.com/Read/533/base-oil-trends

And when you look at the group III+ stocks like the XVHI base stock from Shell, the gaps close to be more or less nonexistant in most areas.

XHVI (Shell Grp III) is superior to most other Group III base oils. The reason is how XHVI is made. Regular Group III base oil is made from hydrocracking and isodewaxing the VGO (vacuum gas oil) from the crude oil distiller. This VGO is the "feedstock" for regular Group III. The undersirable elements of the VGO are "cracked" using a catalyst under high heat and pressure in the presence of hyrdrogen, coverting them to saturated parrafin molecules (the good stuff in any hydrocarbon base oil). The resideual wax molecules in the VGO are isomerized into fully saturated parrafin molecules. The result is an almost pure, fully saturated base oil with a VI of around 120-130.

XHVI (as well as ExxonMobil's ExxSyn) are pure wax isomerates. The feedstock used to make them is not the VGO from the distiller, it is either (1) slack wax, or (2) waxy raffinate. "Slack wax" is basically just what the name implies: it's pure parrafinic wax, about the consistency of Vasoline. It is the byproduct of solvent dewaxing the VGO in the production of Group I and some Group II base oils. "Waxy raffinate" is also a wax byproduct of the refining process used to produce diesel and fuel oil. Waxy raffinate can also be produced synthetically, which is what Shell is doing now using their new GTL (gas to liquid) technology.

To produce XHVI, either of these wax feedstocks are isomerized into a pure, fully saturated paraffinic base oil with a VI of more than 140 and a pour point that is about 10-15 degrees lower than regular Group III. This is the primary benefit of XHVI (or other wax isomerate) over regular Group III: it has a higher VI and lower pour point, as well as being a more chemically pure base oil. When it comes to Group IIIs, XHVI or ExxSyn come the closest to matching the performance levels of PAO.

Let's not forget that even the PAO molecules are not all shaped the same. There are simply narrow spectrum molecular "types" involved, such as dimers, trimers, tetramers, etc.

What ExxonMobil is saying is that their fluids are predominately PAO-based, which means the starting fluid is PAO and occupies a significant volume of the fluid. Also, lest you many claims about group V, remember that many oils contain a 2-ethyhexyl adipate (di-ester) for seal swell, but that doesn't count as a base oil; the percentage is so low that you have to count it as an additive.


Grp III and IV are NOT the same in absolute chemical terms and nobody has stated that they are. But in real terms, they are. Pour point, which is about the only item on a lubricant's spec sheet that PAO has a generally superior valuation for, isnt really relevant anyway, as oils are rated based upon their crank viscosity at a set temperature, not when it stops pouring. If a grp III oil is 6000cP at -35C and a grp IV is 6600cP at -35C, which is the better oil?

So grp IV still needs VIIs and other adds, as well as seal swell and similar chemical additives. Either still need the AO, FM, EP and related additives. Grp III can have excellent viscosity retention, VI, oxidation resistance, NOACK volatility, etc., right on par with grp IV, and equal or better in the case of higher-quality Grp III+ basestocks like Mobil, Chevron and Shell produce. Yet grp III is cheaper to produce because the reactor/catalyst/product handling process is much simpler, and the feedstocks exist at a cheaper price point. And grp III is bad how? All the stuff I said before is false how?

How about some articles to prove me wrong, rather than gut feel?

Remember, Im not saying that all grp III oils are superior to grp IV, or that grp IV is bad or that one should be purchased over another. It is the quality of the final formulation, and how it performs that is most telling. That result is based upon MUCH more than just basestock, and basestock will only tell you for the most part, how well the oil will pour at low temperatures, assuming that we are talking about no aromatic, high end grp III/IV stocks.

Give me a well formulated oil with primarily grp III over a poorly formulated grp IV any day. Im not a grp III or IV apologist. I want optimal performance, not seat of the pants assumptions based upon limited/no/obsolete information that points me to a silly "value proposition" that isnt good for anything.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

If the OP subject line was a question, we know the answer.

Sixto
87 300D
they call me mellow Delo...

The fact that you are mostly around 60-80 means that there will be little notable difference on a good engine in terms of starting performance going between a 5w40 and a 15w-40. Chevron had an excellent SAE paper that Ill have to dig up, showing specifically the benefits and lack thereof of a 5w-40 oil (delvac 1) versus their 15w-40 Delo.

Remember, the real differences in lubricity rates, friction reduction, etc., which might be noticeable in a lab setting, contribute to such a tiny difference in real life that it may not be a real important thing.

Also, look at the PDS for oils. An SAE 40 can very well be thinner at 40C than a multigrade 40wt simply because of the characteristics of the nonlinear temp vs viscosity curve characteristics.

Now, as a rule, one is best off getting as much oil flowing at startup as fast as possible. It isnt a big deal for OTR truckers, as the engines start once and run a long time, the oil is at temperature, and it is easy to make a stable oil with a low spread such as 15w-40. For lots of cold and intermittent operations,a 5w would be smarter, but it is at a cost since getting that spread is tougher.

So, where does that take us? To your duty cycle. Do you usually start up and drive 5 miles or 50 miles in a trip? If the lower, then better fuel economy and performance can be had with the 5w-. With the longer use cycle, the oil will remain at steady state temps longer, so the question starts to focus more on ambient temperatures.

I believe that you want to go towards a 5w-40 diesel oil with up to date add pack specced. A good grp III or IV will do, it is your choice. You could consider a 15w-40 for this application too, and I wouldnt have heartburn. Any of the majors have quality producrs

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Thanks.

5K between changes?

7.5K?

^

Thank you for your perspective.

It's been many, many decades since I had to solve heat and mass transport problems (by hand, often with graph paper) involved in petro-chemical processing.

Your discussion remind me (and it still hurts ) of those days.

It's nice getting a wide range of input.