F+L Week 2015 | 10-13 March 2015
53
ACEA 2012 specification. Another benefit
is low-deposit formation particularly in the
high-temperature regions of the engine such
as the pistons. In addition, the optimised HE-
OCP demonstrates extended shear durability,
which can aid in supporting extended-drain
performance. This presentation reports on
the development of a HE-OCP VII with an
optimised structure that provides robust
low-temperature properties and advantages
in the thickening efficiency, deposits and
extended shear durability.
John Fang is a Senior
Research Scientist and Global
VII CET of Chevron Oronite.
He received his PhD in
polymer science from the
University of Akron in 2002, and worked as a
postdoctoral at Princeton University. From
2004, he has been working at specialty
chemical companies developing functional
additives for lubricant and other applications,
and has five patents and more than 20
publications.
The Versatility of Viscosity
Modifiers across a Range
of Base Stocks and Fuels
Friday 13 March 16:30 | 17:00
DANIELLA BAXTER
Infineum
Viscosity modifiers (VMs) are used in
lubricants to decrease the oil’s viscosity
dependence on temperature and allow the
formulation of multi-grade engine oils that
meet both the high and low temperature
requirements of SAE J300. Although all vis-
cosity modifiers improve the viscosity index
of the lubricating oil, they differ by chemistry,
thickening power and shear stability index as
well as other properties. These differences
play a role in defining other performance
attributes, such as base stock and general
formulation flexibility, biofuel compatibility
and low-temperature pumpability.
The VM type plays a significant role
in flexibility in choosing a base stock,
additive package or pour point depres-
sant (PPD) and in the low-temperature
pumpability of the oil. Whilst many VMs
show robust performance across a range
of components, some VMs can interact
with different base stock waxes and PPDs
in the finished lubricant and, as a result,
show poor low-temperature performance
as measured by Cold Cranking Simulation
(CCS) or Mini-Rotary Viscometer (MRV
TP-1) methods. This means that a change
of base stock or PPD can cause a passing
formulation to fail either fresh oil low
temperature tests or cause failures under
service conditions in the field. VMs play a
role in maintaining a lubricant’s low-tem-
perature pumpability in the field as the oil
ages. Lubricants undergo different ageing
conditions in service, and some types of
driving cycles can lead to oxidation of the
oil, or high levels of biofuel dilution, which
changes the composition of the aged oils.
Some VMs can interact with the biofuel, or
the oxidised components, to cause failing
low-temperature pumpability performance.
In the field, this can lead to catastrophic
engine failures.
The type of VM also impacts the viscos-
ity control of the lubricating oil through
the shear stability index. The thickening
power of the VM determines the amount
of polymer in the oil and can affect deposit
formation. The balance between thicken-
ing efficiency and shear stability is critical
to get the best performance. Field tests are
the ultimate way to show performance.
This paper discusses the choice of the
VM and considers properties above and
beyond simple viscosity index and meeting
the viscometric parameters of SAE J300.
It concludes that formulation versatility,
logistical flexibility and aged oil compati-
bility are also important parameters to be
considered when tailoring the right VM to
meet the needs of the application.
Daniella Baxter currently
works for InfineumUK in the
Technology Deployment
group, specifically with
viscosity modifier and pour
point depressant additives for heavy-duty
and passenger-car engine oil formulations. In
Daniella’s 20 years of working for Infineum,
and previously for Paramins, she has also
worked on developing friction modifiers,
such as molybdenum trimer, as well as on
automatic transmission fluid formulations.
