Yep, that's the one on the "cat", use stuff like INOX or brake fluid but be careful around bodywork and plastics, let it soak for a while and it should work. Good spanners/sockets to use are the so called "Metrinch" type those grab on the flat side of the nut/bolt head so they're capable to undo even rounded of fasteners. Or go for the so called spline drive spanners/sockets but they are rather expensive. If you can swing a hammer there try to give it (the bolt) couple of hits that shock usually loosens up stubborn fasteners too. Use a punch, e.g. brass type so as to avoid damage to the bolt hex sides. When everything else fails use the blow torch to heat it up. Take care with that.
Cheers.
