Ashless Antiwear and Extreme-Pressure Additives 243
The next ILSAC category is ILSAC GF-5, which is targeted to be introduced around mid-2010. The IL-
SAC/Oil Committee has decided that the Sequence IIIG and Sequence IVA tests will be retained to
ensure that acceptable wear protection is achieved in the upcoming ILSAC GF-5 category.
In the heavy-duty diesel engine oil area there are a number of industry standard engine tests that
measure the wear performance. These tests required to meet both industry and engine manufacturer
requirements such as API CJ-4 and various specifi cations from Caterpillar, Cummins, Detroit Die-
sel, Mack, and Volvo. The key wear tests assess the ability of an oil to control valve train or ring and
liner wear under severe operating conditions, which include high-load duty cycles, use of exhaust
gas recirculation, and high levels of soot contamination.
The API CJ-4 category requires three tests that include valve train wear as a pass/fail parameter.
The Roller Follower Wear Test (ASTM D5966) is run in a 6.5 liter V-8 GM diesel engine; it was
initially developed for the older API CG-4 category, which was developed for the introduction
of low sulfur (500 ppm maximum) fuel. However, this test has remained as a requirement in all
subsequent specifi cations. At the end of this 50 h test, the used oil soot level is typically 3.5 to 4.0%.
The level of wear on the stationary pin in the hydraulic cam followers is measured. The Cummins
ISB test (ASTM procedure in progress) was introduced as an industry requirement for API CJ-4.
This 350 h test runs in a 5.9 liter in-line 6 cylinder engine running of ultra low sulfur (15 ppm maxi-
mum) diesel fuel. The fi rst 100 h are run at steady-state conditions to generate 3.25% soot in the oil.
The fi nal 250 h are run under cyclic conditions to stress cam and tappet wear, which are the primary
pass/fail criteria. The third diesel engine test that measure valve train wear is the Cummins ISM
test (ASTM procedure in progress). The Cummins ISM is the third in a series of Cummins heavy-
duty wear tests developed for API and engine builder diesel oil specifi cations. Similar to previous
Cummins M11 HST (ASTM D6838) and Cummins M11 EGR (ASTM D6975) tests, the Cummins
ISM alternates between 50 h soot generation and 50 h wear stages. This test runs for 200 h using
500 ppm sulfur diesel fuel. The used oil typically contains 6 to 7% soot, and the key pass/fail wear
parameters are focused on the crossheads (bridges for the inlet and exhaust valves) and the adjusting
screw for the fuel injectors.
The Mack T-12 test (ASTM D7422) measures ring and liner wear under severe operation using
15 ppm sulfur fuel. This 300 h test runs with a very high EGR rate for the fi rst 100 h to generate
4.3% soot. During the fi nal 200 h, the engine runs over-fueled at peak torque conditions to create
a very severe environment for top ring weight loss and liner wear at the point of top ring reversal,
which are the key wear parameters for this test.
8.5 OUTLOOK
The additives business has experienced an economic upturn in recent years, primarily due to the
imbalance between demand and supply as a result of tight feedstock availability and increased
demand in the Far East region. The basic chemicals used to produce additives are subject to short
supply as new and large capacity has not been effectively added to the manufacturing side for
several years. A number of natural disasters such as the hurricane Katrina certainly made the situa-
tion even worse. The additive suppliers have successfully passed the raw material costs to their cus-
tomers resulting in escalated unit pricing and improved profi tability. The increased volume demand
has been neutralized by several factors, such as longer drain lubricants and the reduction of ash
additives. Despite the push for new engine oils meeting more stringent requirements, a major ratio-
nalization is occurring because of the ability to use additives longer and the recycling of products in
the industry. Consequently, the total additive volume demand is growing slowly. Ashless antiwear/
EP additives are no different from other additives in terms of market demand.
Antiwear additives are a mature function class, and business opportunities in the next few years
w i l l b e mo d e st. T he dom i n a nt p o sit ion of z i nc d it h iopho sph at e s i n eng i ne oi l s is g r a du a l ly d i m i n ish i ng,
but is not expected to be in jeopardy in the near term. Therefore, a total switch to ashless antiwear
additives in engine oils is not likely to occur very soon, but minor changes are in progress.