Daqing experiences long, harsh winters with minimum temperatures dropping below -35°C. Cold-weather starting, operation, and freeze protection for municipal sewage treatment vehicles have consistently been core concerns for procurement entities. This article analyzes a recent case involving the procurement of a National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle by a municipal sanitation department, detailing its technical selection rationale, winter operational strategy, and winning bid price range—providing reference guidance for similar procurements. I. Background and Procurement Requirements In December 2025, the Urban Management Bureau of a district in Daqing issued a tender notice for sewage treatment vehicles, specifying requirements including National VI emission compliance, operational capability across ambient temperatures from -30°C to +40°C, and functions covering sewage collection, solid-liquid separation, and preliminary treatment. The budget was capped at approximately RMB 309,000–387,000 per unit (based on publicly available tender data), with two units required. Following evaluation, Chengli Special Purpose Vehicle Co., Ltd. successfully delivered two National VI Dongfeng 3308 mm wheelbase sewage treatment vehicles, leveraging its proven chassis integration solutions and specialized winter configurations. The vehicle adopts the Dongfeng 3308 mm wheelbase chassis, equipped with a National VI diesel engine and compliant with the CLW5070GSSD6 model certification (referencing MIIT’s official announcement). The superstructure—comprising the sewage tank, vacuum pump, filtration system, and winter thermal insulation kit—is custom-designed by Chengli Special Purpose Vehicle Co., Ltd. II. Technical Selection and Winter Operational Strategy To address Daqing’s extreme low temperatures, Chengli Special Purpose Vehicle enhanced the standard configuration with the following winter-specific measures: 1. Cold-Weather Starting Recommendations - Intake Preheating System: An engine intake preheater is installed to ensure reliable starting at -30°C. - Low-Temperature Engine Oil: Full-synthetic 5W-30 or 0W-30 oil is used to reduce cold-start resistance. - Upgraded Battery: A high-capacity, low-temperature battery (12V, 180Ah) ensures sufficient cranking current. - Starting Procedure: Preheat for 3–5 minutes before starting; avoid aggressive throttle application. 2. Freeze Protection Measures - Pipe Insulation: Sewage piping and valves are wrapped with thermal insulation cotton and protected externally with stainless-steel sleeves to prevent freezing. - Tank Anti-Freeze: The interior tank surface is coated with anti-freeze material; electric heating tapes installed at the tank bottom automatically activate when temperature drops below -10°C. - Antifreeze Coolant: -45°C-rated antifreeze coolant is used to prevent freezing in the cooling system. - Air System Drying: An air dryer is added to prevent ice formation in pneumatic lines, ensuring brake reliability. 3. Routine Maintenance Guidelines - Daily Drainage: Residual liquids in the sewage tank and piping must be fully drained after each operation to prevent cracking due to freezing. - Fuel Filter Inspection: Diesel fuel filters should be inspected every 500 km during winter to prevent wax precipitation. - Tire Pressure Adjustment: Slightly reduce tire pressure (by 0.2–0.3 bar below standard) in winter to improve traction. III. Price and Service Comparison Analysis Based on local procurement practices, the winning bid price for this vehicle ranged between RMB 265,000 and RMB 315,000 per unit (per publicly available tender data), inclusive of chassis, superstructure, winter-specific kits, and transportation costs. Compared to comparable products, Chengli Special Purpose Vehicle’s solution offers the following advantages: - Transparent pricing, no intermediaries: Factory-direct sales model saves approximately RMB 8,000–15,000 versus 4S dealership channels for ident