Mishimoto Expansion Tank for Focus RS/ST with Internal Baffles and Sight Tube

Mishimoto Expansion Tank for Focus RS/ST with Internal Baffles and Sight Tube Upgrade coolant reliability and style — the Mishimoto aluminum expansion tank replaces the fragile OEM plastic unit on 2013–2018 Focus ST and 2016–2018 Focus RS models. Crafted from TIG-welded aluminum, it delivers long-term durability, improved heat resistance, and a clean engine-bay appearance. Internal baffles prevent coolant starvation from overflow ports and reduce sloshing during high-speed cornering, braking, and acceleration. Sight tube provides clear hot/cold level indication for easier maintenance and quicker inspections. OEM cap reuse — designed to work with the stock expansion tank cap for a seamless installation. Overflow nipple on the fill neck supports an optional remote coolant reservoir to remain NHRA legal. Vehicle fitment — engineered for perfect fitment in Focus ST (2013–2018) and Focus RS (2016–2018); installs in under an hour. Finish options — choose Black, Wrinkle Red, or Wrinkle Nitrous Blue to match your build. Mishimoto Lifetime Warranty for added peace of mind. This expansion tank addresses common failure points of plastic OEM tanks while adding performance-minded features and visual refinement. Ideal for street, track, and enthusiast builds seeking reliable cooling and refined engine-bay styling.