I bought 6 qts of GC today at the local AZ today (got it at the $4.39 price by accident) since it was of the 0428x....x vintage. After I got home I looked at the five qts I bought over a year ago at the same store. Had the identical lot number. This would lead me to beleive there is not much turn over in the stock of 0W30 Castrol. The stocker had cleverly mixed German and US 0W30 together on the shelf. Had I not been reasonably alert I might had bought some worthless oil by mistake.