Engines done 65k. As far as I know its never been rebuilt. When I replaced the head gasket, the guides were sound. Had the head checked by PJ Motorsport and it came back with the thumbs up.

The only way I can see the oil getting there is through the breather system, which i've now changed. Havn't driven the motor yet as i'm still in the process of fitting some new bits. So I guess when I drive the motor next i'll find out whether or not the old breather system was the cause.