Called engine sequence tests, these replicate in the laboratory the stresses placed on an engine oil in actual field service. They are the foundation of the quality control system. Developing these tests to the point where vehicle and engine manufacturers, oil marketers and chemical additive suppliers are satisfied with them is arduous, time consuming and costly.

No wonder sequence tests generate such intense feelings in the automotive lubricants industry!

The centerpiece of the new GF-4 passenger car engine oil and its companion API Service Category (SM) is the new Sequence IIIG engine test. It was sponsored by General Motors and co-developed with OH Technologies, a testing parts distributor and quality control monitor based in Mentor, Ohio, and two independent test laboratories, PerkinElmer Automotive Research and Southwest Research Institute. The test measures valvetrain wear, viscosity increase and high-temperature piston skirt deposit formation.

The IIIG was incorporated into the additive industrys Code of Practice in August 2003, after a difficult gestation period, and has been in full-scale use since then for testing candidate GF-4 and API SM oils. Southwest Research and PerkinElmer, both in San Antonio, run the test as do four calibrated laboratories owned by oil or additive companies.

As of Nov. 30, Registration System Inc. in San Antonio had registered 783 tests on candidate GF-4 oils, plus ASTMs Test Monitoring Center reported that 100 reference tests had been completed. Each IIIG test costs almost $38,000 when run on an ASTM calibrated test stand.

Before memories dim, this is a good time to look at how the IIIG test was created and who shouldered the work, and whether they offer a lesson for those who will develop tests in the future.

IIIGs Objectives

The original Sequence III test was placed in service in 1959, and the G denotes that this is the latest iteration, building on its predecessors. It utilizes a modified GM 3800 Series II, 4-cycle V-6 engine, with overhead valve pushrods, and retrofit with a single, in-block flat follower camshaft. Plans are to provide test component availability for IIIG certification testing through 2010, regardless of future design changes within GM Powertrain.

The new G test was intended to provide:

Increased oxidation severity to approximately twice that of the F version.

Increased piston deposit severity to a level that would require detergency performance equivalent to API CE or European ACEA A1.

Increased cam and lifter wear severity, with improved precision over the F test so that oils could be separated in terms of their high-temperature wear performance.

Test developers initially considered separating the wear portion and the oxidation and deposit function into two separate tests. That idea was dropped, and attention then turned to using a custom engine, a 5.7 liter V-8 supplied by GM Performance Parts. Although feasible, the engines power output, increased fuel consumption and test length to obtain the intended severity proved undesirable. The development team once again decided to focus their attention on the 3800 Series II engine, increasing the test length and severity over the IIIF version.

The Hardware Imperative

The most crucial hardware change between the F and the G was the camshaft. Getting this issue right, in order to insure uniform wear results, caused the greatest amount of technical problem solving during test development.

The first IIIG development test was run at Southwest Research in June 2001. Different engine configurations were explored including two types of camshafts, valve spring tension modifications and ring-gapping strategies. Initial test runs used oils with comparable additive packages with varying amounts of phosphorus, from 0.03 percent to 0.095 percent.

During the course of testing, PerkinElmer conducted multiple 10-minute run-in tests, investigating the wear effects of initial scuffing (i.e., adhesive wear caused by spots of localized welding during the run-in). Subsequent tests at both PerkinElmer and Southwest Research Institute confirmed that the best solution to this problem was to initiate a manganese-phosphate coating process on the test camshaft – a solution that had been used once before, on the D version of the Sequence III test, but was dropped from the subsequent versions due to subtle inconsistencies in coating weights and crystal structure formations.

The test development group – which included GMs Sid Clark and Bob Olree, Dwight Bowden of OH Technologies, Southwest Researchs Patrick Lang and PerkinElmers Charlie Leverett – carefully evaluated phosphating processes in order to insure a consistent, fine-grain light phosphate coating on test engine camshafts. After initial concern with the phosphating process, Bowden, whose company has responsibility for obtaining, storing, maintaining and supplying all engine test parts, assisted in identifying an alternative supplier of phosphate coatings. A system involving much closer monitoring of the process from start to finish was implemented for each batch of camshafts. The end result: a very uniform coating weight and crystal formation for every batch of camshafts.

The proof showed in the immediate follow-up test runs. Very good oils generated results near 40 microns of wear, and poor oils near 75 microns. Thus, a principal goal of the test and one which had caused the greatest technical difficulty – providing good wear discrimination – appeared to have been achieved.

Deep in the Matrix

A formal test matrix was set up to confirm the precision and discrimination of the IIIG test. Lubrizols Don Marn chaired the matrix development task force, and Gordon Farnsworth of Infineum chaired the task group that selected the oils to be used in the test matrix.

Three ASTM reference oils (designated 434, 435 and 438), two prototype oil chemistries and two SAE viscosity grades (5W-20 and 5W-30) were recommended and accepted. Camshafts from two separate manganese phosphate batches were also programmed into the matrix. Each oil was scheduled to run four times on two stands at both Southwest Research and PerkinElmer; a total of 24 test runs, the minimum deemed necessary to achieve valid results.

ASTMs Test Monitoring Center director, John Zalar, coordinated the matrix data summary and analysis by industry statisticians. He noted succinctly, The matrix had several purposes. First, to confirm the precision of the test (and it certainly did that) and second, to establish control bands so that test results can be monitored to insure that the test is performing satisfactorily over time.

The test development group, led by GMs Olree, summed up the overall developmental outcome: As a successor to the Sequence IIIF, the Sequence IIIG test provides a high level of confidence and precision in engine oil certification testing for the new ILSAC GF-4 engine oil category.

Getting to this point had involved 50 test runs and cost a total of $1.5 million over a period of two-and-a-half years, plus countless man-hours of technical involvement.

All Together Now

The IIIGs test development group was patterned after the earlier successful IIIF development arrangement. A small, specialized group from the two independent laboratories, guided by Olree, kept technical attention focused and the process moving forward.

But the group didnt operate in isolation, far from it. They reached out, solicited and received cooperation from counterparts in both the engine oil and chemical additives industry.

Infineums Gordon Farnsworth, with 34 years of experience both in test development and test monitoring on ASTM Surveillance Panels, served as a sounding board on a number of technical issues, particularly the difficult matter of the initial run-in scuffing. As did other companies, he observed, Infineum supplied oils used during the developmental process which were critical to solve the early problem of excess wear.

Barbara Dennis of BP Castrol (now BP Lubricants USA Inc.) recalled, We kept informed on the development of the Sequence IIIG by constantly gathering information. The additive suppliers were a tremendous source of information, as were Bob Olrees updates at the ILSAC/Oil meetings. BPs memberships on the ASTM Classification Panel and IIIG Surveillance Panel were an additional source of information and provided an avenue for feedback to the IIIG Development Task Force.

We kept in touch with Bob Olree in both public and private meetings and offered our advice on technical and hardware issues throughout the process, Lubrizols Lew Williams said.

And ChevronTexacos Frank Fernandez, chairman of ASTMs Passenger Car Engine Oil Classification Panel, got his group involved in the process. He noted, Our panel served as a forum to allow members to express their views on the appropriateness of various aspects of the test as it was progressing, and to make suggestions on proposed limits. We also considered how the IIIG could be used in lieu of the IIIF and earlier tests, and how it could be a useful alternative.

Finally, Lubrizols Williams pointed to the success of the overall effort: The performance of GF-4 oils offer a significant improvement over GF-3, a direct result of the fact that the IIIG is equal to at least a double-length IIIF – one of the goals of the test.