Especially the smaller ones that Audi (and other manufacturers use) on the internals of the engines. These bolts came from the cam bearing caps from our 03 A8L 4.2 I'm currently having to replace a chain tensioner. One of the plastic pads let go, thankfully there was no valve damage. I cleaned the carbon build up in each socket and fully seated the torx bit in the head. Only 3 or 4 broke loose without stripping the head of the bolt. I had to use a pair of vice grips to get them all loose. GRRRRrrrrrr.. Needless to say NONE of these bastards will be reused. I will get some regular 6-point head bolts to put this thing back together. Got one side apart, will be doing the other side today. Fortunately there is just enough room to get the vice grips on the heads of these bolts. Otherwise you'd have to drill the heads off.