I am not an expert but first: That's not a cylinder head bolt. It's a stud bolt with a nut securing the exhaust manifold to the side of the cylinder head. If you really had a leaking cylinder head bolt it would be much worse prognosis. Presumably you have checked that the nut is appropriately tightened. Gregorys says 15 - 35 Nm for those nuts. Not too tight cos it's got to cope with lots of expansion when it gets hot. Most likely there is some warping, wear, pitting or corrosion to the manifold face or the side of the cylinder head. To assess, the manifold needs to come off so that the mating surfaces can be cleaned and examined. the face of the manifold can be machined flat and clean. I believe that they can be re-assembled to the cylinder head with an exhaust gasket and that may help if the surfaces aren't too bad. It also helps stop the manifold from cracking which is a common problem on the passenger side. I would consult your friendly local exhaust shop/mechanic first. If you have tools you could do the disassembly and re-assembly
Drives Side