I'm with Mr Stobbs, sump gasket/valve cover sealant. I'm sure it's the loctite stuff I use, with no problems. And that's been used between 2 different metals, steel sump and ally block as well as ally to ally from head to valve cover.
Many thanks all
Am going to go with the above, not only as it sounds right but also reminds me I have a tube of red Nissan sump sealant
Stays semi rubberised ? So should do the job
Thanks for all the pointers and will try rem to post back to show if worked or not
