I recently changed the supercharger oil in my Eaton M90 equipped Pontiac Grand Prix GTP. I took pictures and created a guide to help other GTP or Regal GS owners. You should be checking the s/c oil every
30k miles and topping off or I recommend changing it every 50k miles. It only costs about $15.00 for two 4 oz bottles of s/c oil from GM.
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