General Oil Article Info...fyi

[rsiwicki]

I found this on another forum and thought I would share it here with you all as well to see your comments.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Previous threads have indicated that there is a lot of interest, as well as misinformation (very common when it comes to motor oils) floating around about motor oil. I do not claim to be an expert in this field, but over the past four decades I have worked for and with many oil companies and have been fortunate to know many of the very best experts in this field. These scientists and engineers range from Petroleum Engineers, Automotive test Engineers, Refinery Engineers and Geologists to Paleontologists. I have spent hundreds of hours picking the brains of these people and they have been very generous with both their time and knowledge. I will start trying to share some of what I have learned from them here.

First, let me say that I am not trying to start a debate on the merits of various brands, formulas, additive packages, viscosity recommendations etc. There is an excellent web site for that, "Bob Is The Oil Guy": http://theoildrop.server101.com/cgi/ultimatebb.cgi.Go to this site and you can find out everything you could ever know about oil. Ask a question on this site and you will receive many, excellent, and sometimes opposing opinions, as well as good hard information. Beware tho', I think these guys have hot oil in the morning instead of coffee and then have an oil milkshake for lunch. They tend to live, breath, and drink oil. Some are truly knowledgeable experts, some are quite ignorant, you will have to weed through them yourselves, but will soon come to recognize the experts.

Second, there have been some excellent postings on some other websites concerning motor oil. Those of you interested in Amsoil, synthetic oil (more on that in a moment), oil change intervals (oci), high performance engines and the new oil requirement/standards and wear factors should really read all of the postings by "jestal" on the following link: http://p083.ezboard.com/ffjr13...topic."Jestal" is actually Allen Cline, a 51, maybe 52 by now, year old automotive engineer with General Motors in Detroit. In particular, Allen has worked on the Corvette LS1 and Cadillac Northstar engine projects, including the new supercharged Northstar engine. He has a lot of good information, read All of his posts--it will be well worth your time.

Next, absolutely read this post by "pscholte" about the oil information that has been sent to Audi owners. (But first see the definition of "HTHS" below.) "Pscholte" is also quite knowledgable, but beware, he is, admittedly, an unabashed believer in "GC" above any other oil on the planet. "GC" stands for "German Castrol" and is a special blend, that to the best of my knowledge can only be found at some AutoZone stores. It is also being replaced by a new formula.

To help you understand some of the insider talk/terms, I will explain a few of them as follows. If you see other abbreviations, etc., that you don't understand, post them to this thread and ask for an explanation. I will explain them as best I am able for everyone to understand.

Dino (oil)=this is a colloquialism, or slang expression, in the oil business that refers to refined petroleum oils of Groups I, II, and, arguably, III (more of III below). It has nothing to do with any belief that oil came from decaying dinosaurs, or even from their era. It is simply a term, perhaps originating (my own guess) with the old Sinclair dinosaur trademark. Sort of like calling a computer with an Intel 386 processor a "dinosaur." Obviously not meant literally.

Synthetic (oil)= most oil people consider synthetics to only include those oils that have been formulated by picking and combining specific carbon molecules that the chemists desire in a particular formula. Note that these molecules are extracted from petroleum, so, in essence, all oils start out as "dino" oils, the synthetics essentially just have some undesirable molecules left out. (This may be considered a gross simplification--forgive me.) Additives are then combined with the extracted molecules to add necessary properties to the extracted (synthetic) oil.

PAO=PolyAlphOlefin-a true, and very expensive, synthetic oil base. The only Group IV base oil.

Esters=Very high quality base stocks.

The PAO and esters are the really, really good stuff. As is the new Group III+. The new Pennzoil Platinum appeals to me because it is a blend of these three top, very best, components. Although Allen Cline probably thinks I will be wasting my money unless I am using it on the track; with a supercharged AJ V8 engine I will just "feel" alot better as I watch the speedo climb past 160mph.

Group III = many (most?) oil people consider this highly refined petroleum oil a "dino," but Castrol won a hard fought lawsuit allowing it to call this base oil a "synthetic." I guess the courts and judges knew better than the Petroleum Engineers. So now you may purchase a Group III dino oil that any oil company can label as "Synthetic." Go here for more information about base oil groups and explanations of the different groups: http://www.chevron.com/prodser...shtml

xW-as in 0W, 5W, 10W, etc. "W" simply stands for Winter. As Allen says, unless you are on the northslope of Alaska, (or Northern Canada), you probably will never need anything thinner than a 10W. Nonetheless, for winter, decide what is the coldest possibly temperature you car will encounter, then pick the appropriate "W" weight from the viscosity charts. Anything thinner, as you can see from the HTHS numbers, and you are probably giving up wear protection.

VOA=Virgin Oil Analysis-an analysis of oil straight out of the bottle before it has been used.

UOA=Used Oil Analysis-an analysis of oil after it has been used in an engine for X number of miles.

HTHS=High-Temperature High-Shear; This, I believe, very, very important relatively new test and specification was explained quite well by "MolaKule" on the "Bob Is The Oil Guy" site about a year and a half ago. "MolaKule" is one of the most knowledgeable oil experts I know of and is very much respected for the depth and breadth of his expertise. He is a 60 or 61 year old Physicist and Systems Engineer in Aerospace Propulsion and Systems. MolaKule's "interests" include "Tribology (study of interacting moving surfaces: the science and technology of interacting surfaces in relative motion, including the study of friction, lubrication, and wear), Lubricants and Additives, Thermodynamics, Organic Chemistry," and of course, Physics.

I do not see how his explanation could be improved upon and so it is repeated here, verbatim: "1. The temperature for an HTHS measurement is done at 150C or 302 F, which is the average peak temperature likely to be encountered in a bearing.

2. The oil is mechanically sheared at a rate of 1 x10^6 shearing operations/second.

3. Minimum Oil Film Thickness measurements (MOFT) of operating engines did not correleate well with actual wear in service. A method was devised by which the oil temperature would be elevated to worst case and sheared to determine the optimum viscosity which better correlated with wear.

Three Exxon Researchers found that a minimum HTHS of about 2.8 mPA.s was the MINIMUM HTHS viscosity needed for normal wear, with the higher the HTHS being better for minimum wear. IN general, the higher the viscosity, the greater the HTHS.

For example, in a fleet of taxicabs using a GM 4.3L V6 engine, if the HTHS was 2.35, the startup film was 0.097um and 2.56 um at running; if the HTHS was 2.98, cP, the Startup oil film thickness was 1.231 um while the running film thickness was 3.22 um.

In Dynomometer wear tests using four GM 3.8L engines, the wear mass of a connecting rod bearing was as follows:

HTHS 2.1mass loss (gm.) - 190

HTHS 3.2mass loss (gm.) - 28

For "mains" bearings:

HTHS 2.1mass loss (gm.) - 150

HTHS 3.2mass loss (gm.) - 40

A jump in HTHS by about +1.5 results in approximately 1/5 the wear. Now this relationship is not linear and flattens as one nears a 40+ weight oil.

I should also mention that this test showed little differences in wear between a high quality 5W20 and a 10W30 for oils of close HTHS. For example, The average wear of one of the 3.8L V6's showed a total wear of the Connecting Rod bearings as 48.4 grams for the 5W20 verses 44.3 grams for the 10W30. For a 10W40 oil, the wear was 39 grams!!!

[Mola's comment: I think this test verifies my earlier comments that most daily driver engines can use any oil from a high quality 5W20 to a 15W40 fleet oil.]

Summary: It was found that HTHS correlates better with wear values found in actual oil analysis and actual tear-down measurements than does measuring the oil film thickness in situ."

Now that you know a little about HTHS and its importance, you can see why I like to use Pennzoil Long Life Heavy Duty 15w-40 oil with its high HTHS of 4.3, whereas even good synthetic 5w-30 oils usually have an HTHS of around 3.0-give or take a few hundredths. Note above: "A jump in HTHS by about +1.5 results in approximately 1/5 the wear." So, use the 5w-30 oil if you prefer, get 1/4 to 1/2 more mpg, AND ABOUT 5 TIMES THE WEAR of the 15w-40.

http://theoildrop.server101.co...10499

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[Rex]

Whenever I see a ton of information like that about oil it scares me to think Fred probably knows "all" that and more.

Be interesting to see if he weighs in on it.

[Q45tech]

Yes always concerned me that oil is rated at 212F when oil in bearings is above this.

However comparing a wide tolerance [oil film thickness] US bearing design to a Japanese spec is very error prone.........GM 4.3 V6 vs early Q.

Or use 5w30 in winter and 10w40 in spring and fall and 15w40 in summer to optimize the oil based on probable temperatures in the bearings.

As we know the rad system has a hard time holding 176F in winter and under 195F in summer........plus we drive more agressively in Summer.

Bet the oil/bearing temps change in the same 20F at least with the seasons.

Obviously 10w30 Mobil 1 can maintain low wear rates in a Japanese performance engine from mine and other real world experience.

Whether it will save a domestic with sloppy tolerance is unknown.