Well simon , my half moons were leaking mate , and on boost (only really found out due to rolling road) my oil was spraying out and spraying everwhere , and basically when bonnet was shut it was going over undrside of bonnet and then dripping down onto rocker cover , a simple bit of sealer was needed at bottom ends of half moons and job done , but it can get anywhere and everwhere , and will most probably be coming from that area for sure