[start possible wives tale]i was told that yopu shouldn't use semi or fully synthetic in a old engine [e.g. kent crossflow] or any engine that uses cork gasket as the oil eats the gaskets which then leads to blocked oil ways[/end possible wives tale]

bullshit?

Reason being i've re-built my kent engine and have intended to run it on 15/40 magnetic. However i'd rather go down the sythetic route if it's going to give better protecion?