If you are using a 12-pointr socket, switch to a 6-point socket. They work much better. If that doesn't work, you'll have to use a special socket that looks something like a regular socket but it has some pins inside that rotate and jam up against the spark plug.

I've NEVER had a spark plug with rounded edges. Someone had to have used a set of pliers or the wrong size socket to tighten/loosen the spark plug.

If you rounded off a spark plug your not using the correct socket. Spark plug sockets are 6 point and have a rubber cushion inside to grip and protect the porcelain insulator. There are many different sizes of spark plug sockets 5/8, 13/16, 18mm, etc.

its possible.. first it it is REALLY rounded off you may need just sheer gripping power and a bit of persuasion. hit the bolt with WD-40 to penetrate the metal allow it to soak for 15 minutes or longer. Then see if a pair of vise grips will clamp. if the plug is buried pretty deep into the motor look at the socket you have if it has 12 sides then go get a 6 pt or six sided one deep well if the bolt isnt to rounded off or get a bolt extractor made to remove rounded off bolts. They look like regular sockets but with an edge inside to grab the bolt head or this case the plug but you need to get a deep well one. Hope a six pt will work those bolt extractors can run 30 bucks plus a socket..

Go to a good tool store and pick up a kit like in the link below.

http://reviews.homedepot.com/1999/100051...

Then, put a 1/2 inch (13mm) deep socket over the plug and snap off the porcelain top. Install the extractor and remove the plug.

If it's like most engines, you aren't getting much else in there other than a socket. There are a few types of sockets made that fit "anything", normally little pins that contour to the fastener.

13/16 deep well socket.

monkey wrench

I have a 97 chevy Lumina and I removed 5 of the 6 spark plugs I am having problems removing 1 spark plug from the back of the engine because the nut around the spark plug became rounded when I tried to remove it. Since it is rounded my socket won't grip on to it. Is there a way or a type of socket that will grip on and remove the rounded spark plug.