Shock and Unlock
Halfords Shock and Unlock Cold Spray 400ml combines powerfull penetrating fluids and freezing agents which "shock free" rusted agents and jammed connections.
Good for exhaust bolts and nuts.
Other makes of this style of product
From Frosts, clear liquid more akin to an acid that gets right in there... very long dispensing tube.
Classic, rave form the grave, pen. oil that works and still ha smany fans..
Good standby. Handy for preventing further corrosion, thin oil, useful with wet sharpening stones.