Engine oil viscosity grades can appear to be chiseled in stone. Look in your vehicle owners manual, and youll be instructed to buy SAE 5W-20 or SAE 15W-40 or another specific grade, forever. But in fact, viscosity classifications are pretty malleable. The lubricants industry continually rubs out, argues and rethinks this fundamental property, and publishes its current ideas in SAE J300, the global standard for Engine Oil Viscosity Classification.

SAE J300 is nearly 100 years old, and the past decade saw four updates to the standard. This year alone gave us two shiny new grades, SAE 8 and SAE 12.

How can readers keep score of these alterations? In 2006, Chris May of Imperial Oil (now retired) eloquently summarized all the history-making changes to SAE J300. Now is a good time to share the essentials of his presentation – and to update it to the present.

Lets start by refreshing everyones memory about SAE J300 and what it covers. The classic definition of viscosity is resistance to flow. You know the example: Honey is thick and flows slowly, which equates to higher viscosity. By contrast, olive oil flows rather quickly, equating to lower viscosity.

The technical definition of viscosity is the internal friction between molecules sliding over each other. The smoother the molecule, the lower the friction. Also, as you might guess, bigger molecules get in each others way creating more friction and higher viscosity.

As far as anyone can tell, the first engine oil viscosity classifications came in 1911. Chris May had SAE International search its files, but nothing in writing can be found prior to 1923 and that document doesnt refer to J300, only to Viscosity Classification.

The Kitchen Sink?

Readers would be pretty surprised by that 1923 document. This first engine oil specification covered not only viscosity – 10 grades measured at 100 and 210 degrees F in Saybolt Universal Seconds (SUS) – but also physical properties like flash point, fire point, pour point, carbon residue, color and corrosion properties. Why all the extras?

In the early 1920s, base oil refining was relatively minimal. Pennsylvania Grade crudes were commonly used in motor oil. Their refining often consisted of fractionation for viscosity and chill presses to remove some of the wax. With base oils other than Penn Grade, sulfuric acid sometimes was used to remove aromatic materials. With wax present as well as sediment, tests for pour point and color helped to detect impurities. Flash and fire points would show light ends that may have been used to adjust viscosity. Finally, corrosion tests could detect any acids present. Its almost an afterthought that viscosity was included.

In 1926, the SAE Viscosity Classification standard was edited to exclude all of the oil tests except viscosity. The number of grades was cut to six (SAE 10 to SAE 60) and the SUS viscosities were set at 130F and 210F. To top it off, the viscosity ranges did not run continuously as is the case today. From this point forward only viscometrics are included in the standard.

In 1933 things start to look more like what were used to seeing. There are seven grades (SAE 70 being added), and the ranges are now continuous. In addition, tentative ranges for 10W and 20W at 0F are added, based on extrapolations from viscosity charts.

For the next 17 years, all is quiet on the SAE side. Automakers adopt the extrapolations from the 1933 classification, and add them to their own viscosity standard in 1948.

The Nifty 50s

1950 sees the removal of the SAE 10, 60 and 70 grades, and adds an SAE 5W grade alongside the existing 10W and 20W grades. The only temperatures now are 0F (extrapolated) and 210F, each measured as SUS.

In 1959, the name J300 first appears. The classification system has few changes but they are important. The minimum 0F viscosity for 10W or 20W is waived if the viscosity at 210F is greater than 39 SUS. (It really is starting to look like our modern J300 standard.)

1967 brings major changes and a new name: J300a. The cold cranking simulator test is introduced, with limits at 0F set in centipoise (cP). Also, kinematic viscosity is now to be measured in centiStokes (cSt). Equivalent values are given in SUS, but these are for reference only.

In 1972, SAE J300a is soft metricated. That is, temperatures are shown in Celsius but still represent 0F and 210F. This is a small step but an important one for global and domestic users alike.

At this point the rate of change for J300 begins to accelerate, thanks to a combination of field experiences and the introduction of new test methods. Issues are raised regarding engine oil pumpability at low shear and low temperature, and at the other end of the spectrum, high shear, high temperature viscosity.

1973 sees the addition of an appendix discussing the fact that none of the tests address the sort of low shear, low temperature phenomena which were beginning to show up in the field. And the standards designation is changed to SAE J300b.

In 1975, a new SAE 15W grade is tacked on at the request of Europeans, as a footnote to the SAE 20W grade. Its noted that 15Ws viscosity at 0F must be less than 4800 cP. Another note states that a pumpability test is in the works. The name changes again, to SAE J300c.

Pumping Pains

Next comes J300d, introduced in 1977, with a viscosity classification table looking very much as we see it today. It is now hard metricated with temperatures referenced as 100C and -18C. The pumpability section reverts to an appendix, and an actual pumpability test is promised for 1977 or 1978.

1980 is the next stop on the road, with version SAE J300 SEP80. It adds SAE 5W and 25W, along with the formal inclusion in SAE 15W of the multi-temperature cold cranking simulator. Finally, the long-awaited low temperature pumpability test (ASTM D3829) is added, with passing limits set 5 degrees below the CCS limits for any grade. A small footnote referencing cgs units and defining 1 cP as 1 mPas and 1 cSt as 1 mm2/sec is added.

What follows over the next two years is a shocking series of cold-weather engine failures in vehicles driven in frigid locales such as Sioux Falls, S.D. It turns out that ASTM D3829 pumpability test didnt take into account cooling cycles, which affect how the oil behaves. Depending on how fast and deep the temperature drops, there can be significant differences in the wax structures that form in the oil.

The cause of the engine failures is hard to pinpoint, and both oil marketers and automakers suffer some significant problems. Quaker State (at the time the number one oil in the U.S.) attributes the problem to a combination of dewaxing processes and pour point depressant selection.

Chrysler, on the other hand, saw problems due to metallurgy in its cam shaft and bearing supports. These metals shrink at different rates as temperatures drop; the bearings shrank more than the camshaft, so clearances were reduced to the point where oil flow was choked off and the cam could not turn properly.

Shifts in the 80s

SAE J300 APR1984 is next in the batters box. It includes a provision for running stable pour points, but only for SAE 5W and SAE 10W. The temperature limit is 5C less than the pumpability limit which in turn is 5C less than the CCS limit. There is also language to clarify the labeling of W grades to only the lowest grade for which all tests meet the limits. That is, if an oils CCS meets SAE 10W but pumpability meets only SAE 15W, the oil must be labeled as the heavier grade.

SAE J300 JUN86 adds a reference section but makes no changes to limits or tests. There is also some confusion about naming conventions.

SAE J300 JUN87 complicates matters by including a different low temperature pumpability test (D4684) for SAE 5W, 10W and 15W grades, but leaving D3829 as the method for SAE 0W, 20W and 25W. In addition SAE 60 rejoins the high temperature grades. Stable pour point is eliminated but still referenced in notes as something that should be checked. High temperature, high shear (HTHS) viscosity is mentioned for the first time as something that some manufacturers require and that formulators should consider. In hindsight this version states the obvious: If an engine can crank, then the oil must be able to pump as well.

SAE J300 JUN89 comes next and makes D4684 the sole test method for measuring and setting limits for borderline pumpability. However, D3829 and Brookfield viscosity as well as stable pour point are also referenced in an appendix. There is also continued reference to HTHS viscosity and new methods.

Say SAE!

SAE J300 FEB91 defines that viscosity grades must be on engine oil labels as SAE XW-YY, in hopes of curing the casual labeling practice of leaving off SAE. This update also made all test values critical values. That means for example that for an SAE 30 the viscosity must be within the limits even with the statistical variation that occurs in testing. This exigency will have long-reaching effects. If a state agency tests engine oil and finds it out of grade, for example, it may order a recall of the entire batch without considering the pitfalls of testing.

SAE J300 FEB92 finally brings HTHS viscosity into the document, but only establishes limits for W grades. Multiple procedures to run the test are also allowed.

SAE J300 MAR93 expands HTHS viscosity to cover the non-W grades and splits the limit for SAE 40, to accommodate both heavy-duty and passenger car needs. The capillary viscometer is removed from the approved methods for testing HTHS viscosity, while the multi-temperature CCS (D5293) is finally an ASTM method and taken out of the appendix.

J300 DEC94 has an editorial change.

SAE J300 DEC95 changes the borderline pumping temperature to 5C lower than before, resulting in a 10-degree difference between CCS and borderline pumping.

J300 APR97 reintroduces the capillary viscometer for HTHS viscosity.

J300 DEC1999 lowers the temperature for CCS by another 5 degrees to realign with borderline pumping temperature, again creating a 5C difference in test limits.

J300 MAY2004 removes stable pour point references in the document after 20 years as an interim method. At this time, the test limits are changed to centimeter-gram-second or cgs units.

The Past 9 Years

The trail ends here for Chris Mays valuable review, but not for SAE J300. Since December 2006, more updates have occurred, and we turn for a summary to Isabella Goldmints, who now chairs the SAE Engine Oil Viscosity Classification Task Force.

Goldmints, who works at Infineum LLC, reports that J300 2007 11 – yes, another naming system – changed the High Shear Rate Viscosity at 150C for SAE 40 to 3.5 mPas, with regards to SAE 0W-40, 5W-40 and 10W-40 grades. This is more reasonable than the original value of 2.9 which those grades shared with SAE 30.

J300 2009 01 changed cold cranking simulator limits to be non-critical specifications, as defined in ASTM D3244. This reflects the fact that borderline pumping temperature is more important than low temperature cranking as a specification.

SAE J300 2013 04 added a new grade to the standard: SAE 16. This was a direct request of Japanese engine manufacturers, especially Honda, who were already offering oils in their home market with lighter viscosity than SAE 20s minimum. In addition, the limits for SAE 20 were adjusted to make room for this new viscosity grade.

The most recent change is J300 2015 01, which this year added SAE 8 and SAE 12 to the family of viscosity grades. Goldmints and her SAE task force acted upon the request of a Japanese automaker (Honda again) that already successfully lubricates its vehicles with an engine oil sporting a HTHS viscosity of 1.7 mPas minimum. Honda couldnt label this oil with an SAE viscosity grade because it wasnt defined in SAE J300 – and now it can.

So there you have it. The J300 saga continues to amaze since it is always changing to meet the latest needs of the industry. You can be sure that something new will come along before long, such as a lighter grade to deliver more fuel economy or better cold temperature performance. It just proves one thing: Dont mark your SAE J300 viscosity chart as permanent!