I had heard the same Lorne although plugs I've seen pulled out of GDI Plus 4's, particularly number one can look quite corroded. I use copper slip more for ease of removal though. Feel free to use the article.
An addendum though. The image above was taken before I cleaned the normally hidden right hand bank. The short breather tube fitting into base of inlet manifold can clearly nearly be seen below right hand coil pack but also a patch of oil residue surrounding same. I removed the grey plastic non-return ball valve (quarter turn out of valve cover) and cleaned it out but added a hose clip to upper part where the hose was a not particularly tight fit onto the manifold stub.
Thank you RichardV6. You are kind to your brethren. However, I will remove the bit about copperslip and add the NGK warnings about it. Is that ok? The rest of you post will help the Roadster community mightily.
Lorne
