“The rule of thumb for aging whites is that they most likely peek in 6 years or less. After 6 years they decline.”
I believe the wine in question is a claret of St Emilion district in France. The “blanc” in this case refers to the chateau not the wine.
I don’t as a rule pay much attention to French or European wines. I find them overpriced.
Most of my wine purchases are Western Hemisphere. California, Ohio, Argentina, Chile, occasionally Australia and New Zealand.
I certainly do not consider my self an expert on wine or even knowledgeable. But I do think I have a novices general knowledge.