Sulfurized-Olefin Oxidation Inhibitors for Lubricating Oils
abstract
of the disclosure
Lubricating oil compositions comprising
an effective amount of a sulfurized olefin oxidation inhibitor containing two or fewer sulfur atoms in the sulfur
bridge provide improved oxidative oil thickening in internal combustion engines
as demonstrated in the Sequence IIIF test.
background
of the invention
The present invention relates to
lubricating oil compositions containing sulfurized olefin oxidation
inhibitors.� More particularly,
lubricating oil compositions of the present invention provide improved
oxidative oil thickening in internal combustion engines when an effective
amount of the sulfurized olefin oxidation inhibitor is incorporated in the
lubricating oil compositions.
The Sequence III test has been
completely redesigned for API SL/ILSAC GF-3 as the Sequence IIIF.� The new API SL/ILSAC GF-3 passenger car
engine oil category places a premium on oxidative oil thickening.� In particular, the Sequence IIIF engine
dynamometer test is specifically designed to severely stress engine oils under
high-speed, high-load conditions for 80 hours of continuous operation.� Oxidation control has proven to be a
significant challenge.� Traditional
oxidation inhibitors or inhibitor combinations are largely ineffective in the
Sequence IIIF.� The Sequence IIIF uses a
different engine, unleaded fuel, longer test time, and fewer oil additions than
previous Sequence III tests.� Together,
these changes produce a more severe oxidation test.
Sulfurized olefins have been found
to control oxidative oil thickening, i.e., viscosity increase, in the Sequence
IIIF.� For example, a commercially
available sulfurized olefin marketed by Chevron Oronite Chemical Company adequately
controls Sequence IIIF oxidative oil thickening.�
This
publication summarizes work performed with sulfurized olefins that will deliver
adequate oxidation control when employed in lubricating oil compositions in
internal combustion engines.
details of the invention
As mentioned above, the present
invention provides improved oxidative oil thickening in internal combustion
engines when an effective amount of sulfurized olefin oxidation inhibitor is
incorporated in the lubricating oil composition.
The present invention comprises a
base oil of lubricating viscosity and an effective amount of a sulfurized
olefin to reduce oxidative thickening of a lubricating oil composition when
used in an internal combustion engine.
Base
Oil of Lubricating Viscosity
The lubricant
compositions of the present invention include a major amount of base oil of
lubricating viscosity.� Base oil as used
herein is defined as a base stock or blend of base stocks which is a lubricant
component that is produced by a single manufacturer to the same specifications
(independent of feed source or manufacturer’s location) that meets the same
manufacturer’s specification; and that is identified by a unique formula,
product identification number...