Your comment about using that hex key makes a good point PB. As I'm well known around here as being a man who "knows about cars" - a debatable point I'd suggest! - I've been asked more than once, to help loosen wheel nuts/bolts which have been tightened to such an extant that the wheel brace that comes with the car can't apply enough leverage to slacken them. They are invariably impressed when I deploy my 2ft long power bar and witness the loud "crack" as the nut/bolt is forced to surrender.Many years ago, I bought a hex key for the plug on my classic Panda. (probably 1994) It is a short key, only about 100mm long, so prevents much force being used. I often have to use a larger tool to remove the plug, but always use the short one to refit it.