出，“不同的化学性质对剪切稳定性存在确凿的影响。” 经优化的OCP
显示出可靠的延长剪切稳定性，保留了大部分的结构而没有受以破
坏。这可以进一步提供长换油性能，他说。
剪切稳定性指数用于衡量一种粘度改进剂抵抗由于剪切而出现
永久粘度损失的参数。如Baxter所解释，“对抗剪切稳定性的是增稠
率。”增稠率是衡量在100摄氏度时每单位质量聚合物所增加的粘度。
两者均由分子量所决定。大分子量的剪切稳定性差，但增稠率好，意
味着配方商只需添加较小的聚合物就可以达到期望的粘度等级。
提高了燃油经济性
经优化的OCP可以取得显著的燃料经济性提升，Evonik Oil Addi-
tives动力和工业齿轮油全球产品经理Torsten Stoehr说。他介绍了
分散和非分散梳状聚合物及其较常规PAMA的优势。如果把在发动
机油、自动传动液（ATF）和轮轴油中的效果相加，采用正确配方的梳
状聚合物可以使燃料经济性提高3-4%，他说。梳状聚合物具有一个主
骨架和多条线性侧链。
在对自动传动液进行底盘动力计燃料经济性试验中，Evonik显示
出在油耗上，梳状聚合物较常规PAMA有显著的优势。在新欧洲驾
驶循环（NEDC）的每一章及日本驾驶循环JC08中，一种使用了梳状
聚合物的6.0 cSt ATF的油耗较一种使用了常规PAMA的6.0 cSt ATF
小，在NEDC中的总体优势达到1.2%。对一种使用了梳状聚合物的4.5
cSt ATF也进行了测试，虽然在大多数NEDC中其油耗较使用了梳状
聚合物的6.0 cSt ATF低，但在额外城市行车测试部分，其耗油较高。
the MRV test by a large margin. The conclusion was
that the fresh oil MRV test is not a suitable indicator
of low-temperature performance in the field, Baxter
said. Following some real-world field failures due to
poor used oil pumpability, the Coordinating European
Council (CEC) developed an ageing test, CEC SG-L-105,
that puts the oil through mild oxidation in the presence
of biodiesel and measures MRV performance. This
test correlates much better to field data, Baxter said.
The semi-crystalline OCP in aged oil failed this test as
well, but by a smaller margin. Using the correct ageing
test is necessary to better predict field performance,
she concluded.
FORMULATING FOR LOW-TEMPERATURE
PERFORMANCE
Chevron Oronite’s Alex Boffa, viscosity index improver
technical team leader, and co-author of John Fang,
senior research scientist, said that the key in
formulating for low-temperature performance is to
properly match the base oil, VM, and other additives
with a pour point depressant (PPD). Improperly
formulated oil will give poor results in low-
temperature bench tests or field tests, whether the
