Oil Cooler - VW/Audi 1.8T / Late 2.0L / Mk4 Golf & Jetta / New Beetle / Mk1 TT & More

Product Information

An engine oil cooler is a heat exchanger designed to assist in maintaining stable and adequate oil temperatures to prevent oil breakdown under heavy load conditions. It works by circulating engine oil through a series of small heat conductive passages that are exposed to either airflow (air to oil type) or coolant (water to oil type), depending on the design. Good quality synthetic oil begins to lose protection and lubrication properties generally around 300F and breaks down completely before 500F. In situations where the oil may be approaching this temperature range, it's crucial to bring it back down to standard operating levels.

In an air-to-oil cooler, good airflow is required to ensure the heat is effectively vented. In water-to-oil coolers, engine coolant flowing to the radiator is used to cool the oil. This does not require any additional ducting or fans, which makes this design increasingly popular with carmakers due to additional benefits in engine bay packaging.

Engine oil coolers typically have a thermostat built into the oil cooler circuit that opens and closes depending on the temperature of the oil, to avoid overcooling when temperatures are in a good range.

Engine oil coolers can fail for a few reasons, most commonly due to leaks, blockages, or physical damage. For air-to-oil coolers, the most common failure mode is physical damage caused by road debris or age/rust. Water-to-oil coolers have a different issue. Internal failure can cause coolant to mix with the oil, which will cause a milkshake-like consistency in the oil similar to a blown head gasket.

• External Leaks: Air-to-oil coolers are exposed to difficult road conditions and can be vulnerable to damage from rocks or other road debris.
• Age/Corrosion/Rust: Due to the harsh exposure to the elements, engine oil cooler lines are susceptible to increased levels of corrosion or rust, especially at the fittings. If bad enough, the fittings can become corroded enough to leak, or at minimum lose the ability to service the oil cooler
• Internal failure: Water-to-oil coolers are susceptible to internal failure, which can result in the engine coolant mixing with the engine oil. If gone unnoticed, this can result in engine failure, so it is important to regularly observe coolant or oil quality to ensure the oil cooler is in good shape, especially in older, higher-milage vehicles. Mixing water and oil will result in a “milkshake” style appearance in the fluid.
• Exterior seal leaks: When replacing a water-to-oil style cooler, it is critical to also replace the seals to avoid oil or coolant leaks upon reassembly. These seals can leak either oil or coolant depending on age, mileage, and heat cycling.

About Febi Bilstein

Ferdinand Bilstein’s febi brand is a global leader in the replacement parts market, known for offering high-quality alternatives to original equipment (OE) parts. With a range of over 50,000 technical replacement parts for passenger cars, light commercial vehicles, and trucks, febi ensures that consumers and professionals have access to reliable solutions for maintaining and repairing vehicles. The brand is committed to staying at the forefront of automotive technology, providing parts for hybrid, electric, and hydrogen-powered vehicles, and continuously expanding its product offerings to meet the demands of the evolving aftermarket. febi’s global presence spans over 170 countries, supported by advanced logistics centers that ensure fast delivery and product availability worldwide.

A strong focus on quality sets febi apart, as their products match or exceed OE standards, backed by rigorous quality control and in-house manufacturing capabilities. febi offers comprehensive repair solutions for all major vehicle brands and models, ensuring that critical parts are readily available for professional workshops. With a deep-rooted tradition in mobility and a future-oriented approach, febi is a trusted partner in keeping vehicles performing optimally, regardless of their powertrain or application.