Forgot to answer your earlier question, but generally you should measure how much you drain out and put back the same amount. Since you are slightly over filled now it sounds like i would add a few ounces less than what comes out so you can come down on the stick that 5mm above full.
Even though it says 3.7L is going to be in there it could be vastly different in either direction, which is why its important to measure until you are familiar with your vehicle.
2002 Buick Century 108k - O'reilly HM 5w30/Fram Ultra XG 3980
Filter mag/Cooper CS5 GT/Wearever Platinum Ceramics
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