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Abstract: This article describes 2002-2006 MINI Cooper S Supercharger Oil Service.

Applies to: MINI Cooper S: 2004-2006

Use the following procedure to check and top up Supercharger oil (W11 engine).

Owing to the extreme heat and harsh operating conditions, it is a good idea to check the supercharger oil level on a regular basis. MINI does not specifically recommend a supercharger oil service and no oil is available through MINI parts.

The supercharger on the MINI is manufactured by Eaton. General Motors uses a similar Eaton supercharger and the GM supercharger oil (GM Part number 12345982) can be substituted.

The supercharger has two oil reservoirs; one on the front of the supercharger below the drive pulley and one on the rear behind the water pump. Oil service for each is covered separately.

The reservoir fill plugs are difficult to access, and some disassembly is required to access the rear plug. A small diameter hose may help to facilitate topping off.

Supercharger front oil reservoir, adding oil (W11 engine)
  • Remove engine oil dipstick tube.
  • Using a 3/16 Allen wrench remove oil fill plug (inset).
  • Fill reservoir with oil until it begins to run out (arrow).
  • Reinstall plug and tighten.
Supercharge rear oil reservoir, adding oil (W11 engine)
  • Remove water pump. See 170 Radiator and Cooling System.
  • Using a 3/16 Allen wrench remove oil fill plug (arrow).

Supercharger removed from vehicle for clarity

  • Fill reservoir with oil until it begins to run out (arrow).

  • Reinstall plug and tighten.
Related Topics

MINI Repair & Technical Literature:

Before Performing any Work

Please read Cautions and Warnings before proceeding with any work on your vehicle

Technical Discussion Forums

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2002-2006 MINI Cooper S Supercharger Oil Service


  1. Anonymous

    The SC can be removed without draining the coolant, it's tricky but we have done it, most time we don't because getting the SC off is easier then getting it back on with the water pump still in the car. Plus it never hurts to flush that system too.
    At we only do SC oil service out of the car to make sure we get 6 ounces in the front/pulley end and 3 or 4 ounces in the PTO. This also allows us to really test, look and scope the gut's without taking the whole thing apart.
    Plus if it's not leaking or making noise we see no reason take apart a low mile (less then 75K) SC for just an oil service.

  2. Anonymous

    how many bottles to fil the compressor???

    1. If draining and filling you will need 3 bottles.

      When I top off a compressor, one bottle is usually enough

  3. Anonymous

    How often should the level be checkd and/or changed?

    1. Shops performing the service state they check and top off at 60k.

      1. Anonymous

        Don't take 60K as gospel, I just replace my S/C at 53,000 because the back reservoir was dry as a bone and the gears were DUST.

  4. Anonymous

    are you saying that if I had oil changed at SpeeDee they didn't know and didn't check the other reservoir?

    1. Supercharger oil is not a MINI Factory recommended service. It is however recommended by independent MINI service facilities.

      In other words, speedy lubes will not know to and have not been told to check the oil in it. This is where a good shop or handy owner comes in.

      Use this article to and let us know it works for you. Thanks for the comment.

  5. Anonymous

    does the s/c fail when it out of oil

    1. Yes. The gears will grind into dust. The noise it produces when this happens is often mistaken for a faulty water pump bearing.

  6. Anonymous

    an oil change place is not going to check the oil level of the M45. It can't be checked without removing it from the car. At we check them but it's an extra fee becuase you must take apart the WHOLE front of the car to get the m45 off to be checked on the bench.

    1. Anonymous is not correct URL, you can find them at Thanks.

  7. Anonymous

    Called the Dealer in Memphis,Tenn. as it is closest to me (115miles) and was told they don't service the Supercharger at all! I guess they want to sell you a new one when it fails! I have found a foreign car mechanic here in the town close to me who thinks he can do it in the car and is checking his sources to see what all is involved. I can get the Supercharger oil at my local Chevy dealer as they use Eaton Superchargers on some of there vehicles.

  8. Anonymous

    So my motor is out and in my garage. Im at 78k, I decided to do this SC service. When I removed the drain plug oil barely came out. But it did come out. I re-installed the plug by the water-pump. Removed the other plug, added fluid and it immediately started to come out. Where does this 3 bottles go if one doesnt fit?

    1. Both plugs are for separate reservoirs. You have to fill them both. There is no drain plug. The idea is to suck the old fluid out, then refill the reservoir. Do this for the front and rear reservoirs.

      1. Anonymous

        Thank you. I realized this after I re-read the info a few times.

  9. Anonymous

    I have 79000 miles on an 03 r53 and I'm about to tackle this project. With all the work to remove the front end, what other parts should be serviced/checked while I'm at it. Don't want to have to remove the front end twice ; ). Any gaskets or seals that need to be replaced at the same time?  


  10. Anonymous

    Yeah change the crankshaft position sensor o-ring - very easy to do and very cheap. They always seem to leak so worth using some rtv sealant as well as a new o-ring. You'll know if is been leaking as the front of the engine will be covered in an oily/roadgrime mix of sludge!

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