Thermostatic Sandwich Adapter

The DERALE Thermostatic Sandwich Adapter (Model 25702) is a precision engine oil cooler adapter designed for automotive enthusiasts and performance builders who demand precise thermal management. This sandwich-style adapter installs directly between your engine block and oil filter location, integrating seamlessly into your lubrication circuit without requiring external plumbing modifications. Whether you're upgrading a high-performance street engine, a track-focused build, or a turbocharged platform, this thermostatic adapter provides intelligent oil temperature regulation—coolant flows through the adapter only when oil reaches its target temperature, preventing unnecessary cooling during cold starts and warm-up cycles.

Built from durable aluminum construction, the DERALE thermostatic sandwich adapter features 3/8 inch NPT female inlets and outlets, making it compatible with standard braided hose systems and factory oil galleries. The thermostatic valve mechanism inside senses oil temperature and progressively opens a bypass to your cooler circuit, maintaining optimal operating temperature (typically 180–220°F depending on setup) while reducing parasitic drag during light-load driving. The compact sandwich design—measuring 4.45 x 2.35 x 7.4 inches—fits tight engine bays without requiring custom fabrication, and the integrated aluminum body dissipates minimal heat while housing the precision valve cartridge. This adapter eliminates guesswork from oil cooling strategy, automatically adjusting flow rate as engine load and ambient conditions change.

Engine builders, turbocharged vehicle owners, and long-distance performance drivers benefit most from thermostatic regulation, as it reduces oil degradation under sustained high-load conditions while preserving fuel economy during normal driving. Installation requires only removal of your existing oil filter adapter and sandwich mounting between the block and a remote oil filter head or directly to the engine—no drilling, tapping, or permanent modifications. The 1.98 lb aluminum body is lightweight enough for street and race applications alike, and the NPT thread configuration accepts industry-standard fittings and hose sizes. Whether you're protecting a newly built engine or upgrading an existing platform with enhanced thermal control, the DERALE thermostatic sandwich adapter delivers reliable, automatic oil temperature management that prolongs engine life and maintains consistent viscosity under demanding conditions.