I'm curious about this, and not just because I have the same pesky clicking on my Duetto. Until I read this post, I would have assumed that lighter viscosity oil would increase valve clicking, not reduce it. A heavier weight oil has a greater dampening effect, slows moving parts down, etc., so it seems counter-intuitive to me that the clicking would diminish with the lighter oil. (This is the theory behind using heavier weight tranny oil for noisy old trannies, right?)
Is it possible that the noise was something else, like the oil pump (??), that isn't working as hard to do its job with the 10-30w? Or does the thicker oil just not make it up to the 'clicking' parts?
A related but less interesting question: has anyone found a source for the hex wrench (14mm, I think) to fit the cam cover bolts?
1962 Giulia Sprint 1600, 1967 Giulia Super