As countries around the world attach more importance to carbon emissions and more
stringent requirements are put forward for vehicle emissions, hybrid vehicles,
which can significantly reduce emissions compared with traditional fuel
vehicles, as well as low-viscosity lubricating oil, have become significant
trends in the industry.
In this article, a total of nine vehicles of 48 V mild-hybrid models and
full-hybrid models are tested. Using three kinds of low-viscosity lubricating
oil and driving a total of 120,000 km in environments with low temperature, high
humidity, high temperature, or high altitude, the engines are then disassembled
and scored. The effects of the four extreme environments on the engine
starts–stops, ignition advance angle, engine power, state of charge (SOC),
acceleration performance, and oil consumption characteristics of hybrid vehicles
are studied; the oxidation characteristics and iron content change
characteristics of low-viscosity lubricating oil are analyzed; and how
lubricating oil protects the engine in durability tests are verified.
According to the test results, in the low-temperature environment, for
full-hybrid models, the number of engine starts–stops and the running time are
significantly increased, while the SOC is generally high. In the
high-temperature environment, for full-hybrid models, the ignition advance angle
of the engine is reduced, which inhibits the risk of pre-ignition; the
characteristics of the SOC are similar to those in the high-humidity and
standard-temperature WLTC working conditions; the oxidation rate of lubricating
oil has almost no effect on full-hybrid models; for mild-hybrid models, oil is
prone to oxidation and decay. In the high-humidity environment, the oil
consumption rate deteriorates with the increase in relative humidity under the
same load and engine speed, and the accumulation rate of iron content in oil
increases compared with that in the high-temperature and high-altitude
environments. In the high-altitude environment, with the increase in altitude,
the engine power of full-hybrid models decreases at the same engine speed,
resulting in a decrease in the engine’s charging efficiency to the battery, so
that the battery level could not be relatively stable. The acceleration
performance of both hybrid models decreases significantly with an increase in
altitude. After the engines are disassembled, it is found out that with the
protection of low-viscosity lubricating oil, the wear of engine parts is very
small, and the deposit control is good.
