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.

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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.

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone