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

Mishimoto Expansion Tank for Focus RS/ST — Internal Baffles & Sight Tube Upgrade reliability and style with the Mishimoto aluminum expansion tank designed specifically for 2013–2018 Focus ST and 2016–2018 Focus RS. Built to replace the fragile plastic OEM tank, this TIG‑welded unit delivers long-term durability and a clean engine‑bay look. Internal baffles prevent coolant starvation from overflow ports and reduce sloshing during hard cornering, braking, and acceleration. Integrated sight tube provides clear hot/cold level viewing for easier maintenance and quick inspections. Durable construction — TIG‑welded aluminum resists cracking from constant temperature cycling unlike stock plastic tanks. OEM‑cap compatible reuses the factory expansion cap and includes an overflow nipple on the fill neck for an auxiliary catch tank (NHRA compliance option). Fast, precise fitment — engineered for easy installation in under an hour with perfect fitment and included hardware. Finish options — choose Black, Wrinkle Red, or Wrinkle Nitrous Blue to match your style. Mishimoto Lifetime Warranty — backed for life for peace of mind. This expansion tank combines functional improvements—improved coolant control, easier level checks, and superior durability—with aesthetic customization for your Focus RS or ST. Ideal for daily driving, track days, and performance builds.