. fluid level was low in my rear axel. ..What is the normal cost for this procedure? on 2007 Pontiac Solstice

I bought the car from an individual so,I have no history.Car fax gave the car passing marks.

Asked by for the 2007 Pontiac Solstice
I read on another site that there is a recall on this. This site does not report the recalls that there actually is for this car. I read yesterday on a recall TSB list that there are 3 recalls.