Description Reviews MINI Cooper S Expansion Tank! These fail from time to time on R52 or R53 MINI Cooper S's. Very early on they all failed right at the seam and that unit was a clear milky white color, but by early 2003 they had a fix for the problem and that was a new tank that is still milky in but more of a tan in color. They also updated the cap on the inside and the seal. You can tell by the bright blue seal inside of it. Now a days we see some leak from the seam and some from the cap. We do sell the cap by it's self if needed. This is a brand new OEM design and comes with the new updated cap. Comes with a 2 year unlimited miles warranty from MINI! Want more under bonnet bling with a permanent solution? Try the tank from Forge.