The Derale 35621 is a thermostatically controlled LS engine oil cooler bypass adapter kit. It uses a built-in 180°F thermostat so that cold oil bypasses the cooler on startup, then at 180°F the internal valve closes and routes all oil through the cooler while maintaining constant pressure. This helps the engine reach operating temperature sooner and keeps oil temperature controlled once warm. The billet adapter uses large -10AN ORB inlet and outlet ports for high flow and is shaped to clear most long tube headers on LS swaps.
Specifications:
- Type: thermostatic LS oil cooler bypass adapter kit
- Thermostat: built-in, activates at 180°F
- Operation: bypasses cooler when cold, full flow to cooler at 180°F with constant pressure
- Cooler ports: -10AN ORB inlet/outlet; additional 1/8" NPT ports
- Flow: up to 20 gallons per minute
- Pressure rating: up to 200 psi
- Construction: 6061 billet aluminum, black anodized, Viton o-rings
- Clearance: clears most long tube headers for LS swaps
- Application: GM LS family engines
- Part number: 35621
Fitment: GM LS family engines. Confirm engine and cooler fitting size before installation; -AN cooler fittings are supplied by the installer.
FAQ
What is the Derale 35621?
It is a thermostatically controlled adapter that adds oil cooler ports to a GM LS engine and manages when oil is sent to the cooler based on temperature.
At what temperature does the thermostat open?
The built-in thermostat activates at 180°F. Below that, oil bypasses the cooler; at 180°F the valve sends all oil through the cooler while maintaining constant pressure.
What ports does it use?
It has -10AN ORB inlet and outlet ports for maximum flow, plus 1/8" NPT ports. It flows up to 20 gallons per minute and is rated to 200 psi.
What is it made of?
It is machined from 6061 billet aluminum with a black anodized finish and uses Viton o-rings.
Does it work with LS swap headers?
Yes. The adapter is shaped to clear most long tube headers used in LS swaps. Confirm clearance for your specific header before installation.
