[Arctic]

I would say 15mm the original ones are I think 20mm in length, 6mm thread and an 8mm head, so a 8mm headed 6mm thread and 15mm length would suit.

Those that have had the cam cover pieced by over tightening the original bolt or one longer, I have in the past used a number plate plastic screw as a grub screw 5mm, but then you need a 10mm length bolt so as not to push on the grub screw when fitting the engine cover, but as already stated if you do have a pieced cam cover and the engine cover is removed with the engine running just insert the bolt a third in to stop the oil spitting out.