Liet,

Another old wives tale, Synthetic oil drains down into the pan overnight.

Synthetic oil has superior film strength. We did oil experiments when I worked for IBM and an almost invisable film of oil is just as good as a puddle of oil. So even though it seems that Synthetic oil drains back to the pan, the film of oil is still there.

Because one person had premature valve wear does not prove synthetic oil is NG. If you have data that thousands of engines had valve wear with Synthetic oil and thousands of engines didn't have valve wear with non synthetic oil, then you might have some proof.

P E H