Can I call him Grandpa Wen?

I asked the students about Wen Jiabao and Hun Jiantao. What, I asked, does a Prime Minister do in China? They told me that PM Wen looks after the day-to-day running of the government. I then asked them what a President does in China? Their answer was that President Hu looks after other things and can fire the PM if he wants. So, they weren't clear on what the two men's responsibilities were. I thought of asking if their relationship was like Batman and Robin, the Lone Ranger and Tonto, but they wouldn't have understood.

The students were uncomfortable with my idea of calling Wen Jiabao, Grandpa Wen. I call him Grandpa because that seems to be the public image he is cultivating on Chinese television.