I. Case Background: Sludge Removal Truck Procurement Requirement of a Municipal Sanitation Department in Daqing, Heilongjiang Province In early 2025, a municipal sanitation department in Daqing issued a public tender for blue license plate sludge removal trucks to support urban drainage network cleaning operations. Given the region’s extremely cold winter climate (minimum temperatures reaching -35°C), the bidding proposal emphasized the vehicle’s low-temperature starting performance and freeze-protection design. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. (“Chengli”) won the bid with its Dongfeng single-cab, blue license plate, 5-cubic-meter sludge removal truck solution, delivering three units at an approximate unit price of RMB 125,000 (based on publicly available tender information). The vehicles are now operational in Daqing, with customers reporting stable winter performance. This article analyzes this case from the perspective of winter operations in northern China, outlining key maintenance practices, cold-weather starting recommendations, and anti-freezing measures for blue license plate sludge removal trucks. It also reviews Chengli’s after-sales service commitments, providing reference guidance for other municipal sanitation authorities. II. Winter Maintenance Essentials for Northern Regions: Specialized Recommendations for Sludge Removal Trucks Daqing experiences extremely low winter temperatures and frequent snow/ice accumulation. After operation, sludge removal trucks often retain residual sludge and moisture; if not promptly addressed, this may cause valve freezing and cracking, or hydraulic system failures. Based on recommendations from Chengli’s after-sales technical team, the following aspects require special attention during winter maintenance: Hydraulic System Freeze Protection: Hydraulic oil must be replaced with low-temperature-grade oil (e.g., L-HS32 or L-HV32), featuring a pour point as low as -35°C to prevent oil line blockages. Hydraulic oil level and seal integrity should be inspected weekly; any leakage detected requires immediate replacement of seals. Drainage Pipeline Freeze Protection: All residual liquid must be fully drained from the sewage tank and pipelines after each operation to prevent ice expansion-induced pipe rupture. Insulating sleeves or electric heating tapes may be installed at pipeline joints, supplemented by antifreeze solution for pipeline flushing. Chassis and Battery Maintenance: Dongfeng chassis are covered under nationwide warranty; however, battery electrolyte density must be checked regularly during winter (recommended ≥1.28 g/cm³). Battery capacity drops by over 30% in low temperatures; therefore, batteries with ≥75 Ah capacity are recommended. Chassis lubricants must be replaced with winter-grade oils (e.g., 5W-30 engine oil). Tires and Braking System: Tire pressure should be adjusted upward to the upper limit of the standard value (e.g., 2.8–3.0 bar) during winter. Brake fluid moisture content must be verified (≤3%) to prevent brake failure due to freezing. Snow chains or winter-specific tires are recommended. III. Cold-Weather Starting Recommendations: Critical Measures for Operation at -35°C The diesel engine equipped on the Dongfeng single-cab, blue license plate sludge removal truck (model reference: CLW5070GSSD6, per official announcement parameters) requires special handling for reliable cold-weather starting. Chengli’s technical team provided the following startup recommendations upon delivery: Preheating System Usage: Prior to starting, activate the intake air preheater (grille heater) for at least 30 seconds, or use an optional engine block heater to raise coolant temperature above 20°C. Direct cranking without preheating is strictly prohibited, as it may accelerate fuel injector wear. Fuel Selection: Use No. -35 diesel fuel (cloud point: -35°C) to prevent wax precipitation and fuel filter clogging. Diesel anti-gel additives should be added to the fuel