unless there is good reason to change it. First, find out where the leak is coming from. Just get under the car, if you can, and do a visual to see what gives. Changing a head gasket is not just a simple matter of nuts and bolts. I agree with Bill R., it's not that clear cut to lend advice in this matter when we don't know your skill level. There are many issues, and the cost could be very high if you have someone do the repair.