Sinister Diesel's new Coolant Reservoir is made from 6061 aircraft grade aluminum which is TIG welded and pressure tested for maximum strength. This fabrication method makes Sinister’s tank significantly stronger than factory tanks which are molded from two plastic pieces which are sealed together causing stress, cracking and leaking. In addition, aluminum dissipates heat in the coolant system, improving performance and longevity. Sinister’s Coolant Reservoir uses a the factory cap (upgraded caps are available!) and features sight glass for easy level inspection. It is a direct, bolt in replacement for your stock reservoir and can be installed with basic tools in less than 30 minutes.