SAJ, There was NO need to add that last line!!
On one of my cars, I'm down to a marginal clearance but I didn't think of surfacing them at an angle then - that came later but I'll make sure next time. To prevent seizing, I use Molykote 1000 (Dow Corning). I looks to have a fair bit of Cu in it too. Always been good and I don't think I wiill ever finish the tin