Billet Coolant Reservoir for BMW M5

Just ordered a billet coolant tank to replace the stock plastic reservoir for my M5. The details below are from the RK Autowerks website (mages from RK Autowerks).


Billet reservoir designed and machined in house to remedy the failing stock plastic reservoir. Our all metal construction reservoir ensures leaks are not an issue anymore. Constructed of 6061 billet aluminum, you know you have a lifetime product and don’t need to worry about leaks anymore. Utilizing the stock cap also retains the pressure bleed off like designed by the OEM. All of the OEM connecting points are utilized and the quick connect fittings slip right on. This is a plug and play solution which even utilizes the stock sensor ensuring there won’t be any issues with level readings.


The OEM plastic reservoir is known to leak causing damage of the injectors and coils. This leads to vehicle downtime and potential engine damage. Simply replacing the OEM reservoir with another one is an unknown with how long it may last.


  1. 6061 billet CNC construction
  2. OEM factory cap retained
  3. OEM connections utilized like stock
  4. OEM sensor utilized for level reading
  5. O-ring sealing to ensure no leaking
  6. Internal baffling to dampen fluid transfer throughout the reservoir


  • MSRP $1250
    • Black Anodized Coating – $50

Models Supported

– 2018+ | M5 | F90
– 2019+ | M8 Coupe, Convertible, & Gran Coupe | F91, F92, F93


  • The customer will have to re-use the stock coolant sensor probe, which pulls out of the OEM reservoir. In certain cases, it does not slide out smoothly and you may need to trim around the sensor to remove it. Additional o-rings are provided in the situation where a stock o-ring is damaged.