During the 40-year gap between the Sequence IV and IVA, wear was measured in the Sequence III and Sequence V. All of the original test engines were push-rod assemblies until the Sequence VD was introduced. It was run in a four-cylinder overhead cam engine, as was the Sequence VE. The Sequence VG reverted to a V8. The test duration varied from 288 hours to 216 hours. Maximum wear was measured on the cam lobes.

The Sequence III evolved into the Sequence IIIC and Sequence IIID, which were V8 engines, to the Sequence IIIE, using a V6. All of these engines were designed with push rods. This test also has varied over time from 64 hours to 100 hours. It measures cam and lifter wear, both average and maximum.

The original Sequence IV test was run in a 1963 V8 Chrysler engine and measured high temperature and high speed cam valvetrain wear (in block cam and lifters). The test was 24 hours long and included special valve springs which overloaded the cams and tappets. Cam and lifter wear was measured. It did not discriminate and was not used much at all. I have to admit that Im not old enough to remember any original Sequence IV tests being run or any test results.

When the Sequence IVA was introduced, it didnt immediately become the primary wear measurement. It used a four-cylinder Nissan engine and measured cam lobe wear over 100 hours. I think Nissan may have introduced it to establish a presence in the system. They also had some field problems and concerns with the transition to low-phosphorus oils. For the first few years, it was run along with the Sequence VG as an alternative to Sequence VE. In the meantime, so long as the oil contained at least 0.08 percent weight of phosphorus, the Sequence IVA was not required.

When the GF designations were first introduced, the Sequence IVA was run to demonstrate that there was a wear test designed specifically for modern gasoline-fueled engines. It also gave the Japan Automobile Manu­facturers Association an entree into the new engine oil categories.

That all changed with the introduction of API SL category oils in 2001. The Sequence IVA became a required test for approval as an API SL or ILSAC GF-3 engine oil. It has remained one of the required tests through API SN and GF-5. It has been a well-behaved test with little or no drama associated with it.

You know that couldnt last. With the upcoming introduction of GF-6, there will be a new version, the Sequence IVB. Toyota is now the source of the engine, and the procedure seems to have taken a dark turn. To date, the test has not been finalized and is still undergoing development, although it looks like there may be an end in sight.

Its Never Easy

Developing a new engine test procedure is laborious to say the least. Ive mentioned before that there are a number of steps that must be completed before the test can be finalized and inserted into any performance category.

In 2014, Don Smolenski of Evonik presented a webinar for the Society of Tribologists and Lubrication Engineers describing the perils of engine testing. Listening to that presentation, I was reminded of how difficult the whole process has become.

The point of engine testing is to approximate, as closely as possible, actual driving conditions. Field testing would be better but is too expensive and time consuming to be acceptable, although it often forms the basis of engine test development. Bench testing would be great, except it doesnt come close to approximating actual field conditions.

To develop an engine test requires an engine (duh) as well as a set of conditions (test length, operating parameters, reference oils and so on). Once a procedure is established, the test is run in several labs in replicate to determine if it is measuring what it is meant to measure and doing so consistently.

The Sequence IVB is sort of a new test since it is new hardware, but it is meant to correlate with the Sequence IVA. The bridge between the two is the reference oils. I havent stayed up to date on all of the permutations of the test that the ASTM Sequence IV team has gone through but do know they have tried a bunch of them. Currently, the final proposed procedure is going through matrix testing to confirm the precision of the test as well as its ability to discriminate between passing and borderline failling oils. That work was expected to be completed last month. Given the process to arrive at a new API category, it will be about two years before GF-6 oils are available for purchase.

Fueling the Debate

I mentioned that there was another test that has been in the industry news. Thats the Sequence VIE (and VIF). This is the fuel economy test used to determine what fuel savings can be achieved due to engine oil. To date, most of the benefit seems to be mainly due to viscosity. Thats why you see the viscosity of engine oils continuing to drop.

When I started out in this industry, the prevailing viscosity was SAE 30 for summer driving and SAE 20W-20 for winter. SAE 10W-30 was an alternate recommendation. By 1980, SAE 5W-30 was the new kid in town. Today its still in general use along with SAE 5W-20, although SAE 0W-30 and SAE 0W-20 are beginning to make some gains. In Japan, Honda recommends an SAE 0W-16, and very recently, JAMA began work to develop an SAE 0W-8 for introduction in 2019.

Friction modifiers are also included in most engine oil formulations and do add to the fuel economy benefit. However, they dont appear to impact the Sequence VIE very much.

The history of fuel economy testing is pretty fascinating since it started out as a vehicle test rather than an engine test. In fact, it was a five-vehicle test and was documented in SAE J1423 (Class­ification of Energy-Conserving Engine Oil for Passenger Cars, Vans and Light-Duty Trucks). The procedure ran on a chassis dynamometer test protocol used to measure emissions. The five cars represented the marketplace for vehicles at the time.

The five-car test protocol yielded some positive though not too exciting results, but was soon replaced by the Sequence VI. This is a single engine test which measures the difference in fuel consumption between a reference oil and the fuel economy candidate. I think that the baseline oil is an SAE 20W-30 and the flush oil is SAE 20W-40, so the benefit due to viscosity should be apparent.

Sequence VID was the test for the current categories, GF-5 and API SN Resource Conserving. However, weve run out of engines to run the test and, for the time being, we are faced with provisional licensing for any new oil approvals. There are new Sequence VI procedures (VIE and VIF). There is a process underway by which the Sequence VIE can be used to give similar results to the Sequence VID. The proposal is to take several GF-5/API SN Resource Conserving approved oils and run them in the Sequence VIE. The results would be statistically analyzed and Sequence VID equivalent limits could be set using the Sequence VIE procedure.

As for the Sequence VIF, it was developed to cover the very-low-viscosity engine oils, particularly SAE 0W-16, which could not be evaluated using the Sequence VIE procedure. It does use the Sequence VIE hardware.

What I find really interesting is that an SAE paper presented in April reports that fuel economy benefits identified by Sequence VID are greater than those identified by a chassis dynamometer procedure. What goes around comes around!

As I read over this column, it occurs to me that if nothing else, nomenclature can add to the fun and the confusion. I hope that at least you can get an idea of what a struggle it can be to try to keep the oil category process going.

Industry consultant Steve Swedberg has over 40 years experience in lubricants, most notably with Pennzoil and Chevron Oronite. He is a longtime member of the American Chemical Society and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at steve
swedberg@cox.net.