Government procurement case of Dongfeng D6 sewage treatment vehicles (blue license plate) in Dongguan: Interpretation of winter operation and bidding proposal. In southern coastal cities such as Dongguan, municipal sanitation authorities face unique challenges when procuring special-purpose vehicles—high-salinity air accelerates chassis corrosion, frequent rainy-season operations test the durability of sealing components, and sustained high-intensity operation places significant demands on core vehicle components. This article takes the recent procurement of Dongfeng D6 blue license plate sewage treatment vehicles by a municipal sanitation department (hereinafter referred to as 'the unit') as an example, integrating products and services from Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli'), to provide an in-depth analysis of winter operation guidelines, tender proposals, and vehicle selection logic—supporting informed government procurement decisions. For reference to publicly released tender information, contact Chengli sales manager Zhang Yue at or call for detailed solutions. I. Case Background: Procurement Requirements of a Municipal Sanitation Department in Dongguan In 2025, the Urban Management Bureau of a district in Dongguan planned to procure a batch of blue license plate sewage treatment vehicles to address local sewer network maintenance and emergency response needs. Following preliminary research and open tendering, the unit ultimately selected the Dongfeng D6 chassis equipped with Chengli’s proprietary sewage treatment superstructure. According to publicly available tender information, the unit price per vehicle was approximately RMB 135,000, with a total budget capped at RMB 165,000; five units were delivered in total. Customer feedback indicates that these vehicles are currently deployed primarily for sewage pumping, drainage, and temporary treatment during the rainy season—entailing high operational frequency and stringent requirements for corrosion resistance and sealing performance. II. Winter Operation Design: Comparison of Northern Winter Maintenance Practices vs. Southern Humid-Heat Conditions Although Dongguan is located in southern China where winter temperatures rarely drop below 0°C, the concepts of 'freeze protection' and 'maintenance' during winter operations differ significantly between regions. For northern users, winter maintenance focuses primarily on antifreeze coolant replacement, battery insulation, and diesel fuel grade selection; southern users, by contrast, must prioritize 'anti-corrosion coating' and 'sealing component durability' under humid-heat conditions. Taking Chengli’s Dongfeng D6 blue license plate sewage treatment vehicle as an example, its chassis employs Dongfeng’s original factory anti-corrosion process, while the superstructure receives additional anti-corrosion coating specifically engineered for southern high-humidity environments—effectively slowing down erosion of the frame caused by rainwater and high-salinity air. Real-world usage has validated this design: at a street environmental maintenance unit in Dongguan, identical model vehicles operated for nearly two years show no visible chassis or tank corrosion, and sealing gaskets retain excellent elasticity without leakage issues. III. Cold-Weather Starting Recommendations and Freeze-Protection Measures (Addressing Both Northern and Southern Requirements) For low-temperature winter environments in northern China, Chengli vehicles undergo targeted factory adjustments. For instance, in a case involving five water-sprinkling vehicles (model CLW5070GSSD6) deployed at a sanitation station in Heilongjiang Province, users reported smooth engine starts even at -15°C—attributable to Chengli’s standard-fit cold-start assistance system and premium-grade antifreeze coolant. In southern regions like Dongguan, although freezing temperatures are not a concern, high humidity dur