QF gasoline engine oil (equivalent to SF oil) has been developed
by using Daqing base oil. The Daqing base oil is highly paraffinic,
excellent in temperature-viscosity performance, low in aromatics
and sulphur content and high on nitrogen content as compared with
the foreign base oils of the same category. The antioxidation
performance of Daqing base oil, however, is not adequate,
especially in the latter period of oxidation. The newly developed
QF oil must meet the specification which requires a viscosity
increase not exceeding 375% after 64-hours' oxidation. In
recent years several foreign oil and additive corporations had made
efforts in formulating high grade engine oil based on Daqing base
oil, but their formulations could not meet the above mentioned
specifications. Some effective antioxidants were screened by
simulated oxidation test using suitable Daqing base oil. The
increase of viscosity of this base oil in the latter period of
oxidation has been improved. Accordingly, RIPP collaborated with
Gaoqiao Petro- chemical Corporation have successfully developed a
10w/30 QF gasoline line engine oil conforming to the specification
on SF gasoline engine oil.
The total number of imported passenger cars and those
manufactured by jointventure in China has been increasing rapidly
during recent years. Most of these cars require multigrade QF
(equivalent to SF) oil for their engines. China is only producing a
limited amount of QE (equivalent to SE) oil with imported additive
package. Hence, there is an urgent need for QF gasoline engine oil
in China.
Daqing base oil is highly paraffinic and is excellent in
temperature-viscosity performance. However, its anti-oxidation
performance is not satisfactory as its viscosity increase
remarkably in general after oxidation. Therefore, to pass MS
sequence IIID engine test, the viscosity increase of Daqing base
oil must be kept below 375% of its original value after 64 hours
testing while the wear of cam and lifter system is also within the
allowable limits