Sourced from TOPRAN, this thermostat coolant (503 239) combines precision engineering with durable materials to meet the demands of everyday driving and extended service intervals. Technical specifications — Opening Temperature [°C]: 102 °C, Housing Type: 0, Supplementary Article/Info 2: Nylon, Housing material: Plastic — are verified against the OEM data sheet to guarantee fitment accuracy and performance parity with the original equipment. Verified to fit BMW models. All compatibility data is cross-checked against the TecDoc database — select your vehicle to confirm the part matches your specific engine and year. This part supersedes original equipment references: 001-10-21464, 004-025-0014, 08.19.228, 11 53 7 552 403 and 103 more. Matching these numbers confirms a like-for-like replacement with no loss of function. TOPRAN is a recognised supplier of automotive replacement components to independent workshops and dealer networks across Europe. All parts are sourced from authorised distribution channels and carry full manufacturer traceability — you receive exactly the same component supplied to professional garages and dealer workshops. If fitment or specifications do not match your vehicle, our technical team can help identify the correct alternative — use the vehicle selector or contact us with your VIN for a guaranteed-fit recommendation. Replacing worn components on schedule preserves your vehicle's safety, reliability, and resale value — and aftermarket parts from established brands deliver OEM-equivalent performance at a fraction of the dealer price. Every part is dispatched from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.

TOPRAN, part of the Hans Thomsen Group headquartered in Hamburg, Germany, is a growing independent aftermarket brand focused on providing quality parts at accessible prices. TOPRAN offers a comprehensive range covering engine, cooling, electrical, braking, and body components for European vehicles. All TOPRAN products are manufactured to meet OE specifications and undergo quality testing before distribution. Combining German quality management with competitive pricing, TOPRAN is an excellent choice for cost-conscious motorists and workshops who do not want to compromise on part quality.