You're right, type XL5 produces the dates in the correct format. Type XLS however, produces them in the wrong format and I have not find a way to correct the format.

However, XL5 have the problem of wrong name casing for the file. I guess I need to use XL5 and then rename the file to correct casing using MoveFile API.

Net v zhizni sovershenstva (don't know how to translate).