Sinister Diesel 01-16 GM Duramax 6.6L Coolant Reservoir (Degas) Cap - Gray

If you're working on a 2001-2016 GM truck with a 6.6L Duramax engine, this coolant reservoir cap from Sinister Diesel is a solid option. It's designed to replace the factory cap on OEM or Sinister Diesel coolant reservoirs, offering both improved looks and reliable function. This cap is rated for 15 PSI, helping to maintain proper pressure in your cooling system.

This cap is CNC machined from T6-6061 billet aluminum, giving it a strong and well-built feel that stands out from stock plastic. It also includes an interior pressure relief system, which is a smart feature that ensures it will continue to function correctly even if the gasket has an issue. The anodized gray finish and etched Sinister Diesel logo give it a custom appearance that many Duramax owners appreciate.

This cap is a direct replacement for the factory cap and fits a wide range of GM trucks, including models like the Chevrolet Silverado 2500 HD and GMC Sierra 3500 HD. It's a straightforward part to install, often requiring no special tools beyond what you'd typically have for basic engine bay maintenance.