I went up to the little hick town north of me today to see if the Walmart there carried Mobil TDT. Unfortunately they had everything but the TDT. Not having any luck at Walmart I decided to go across the street and snoop around Autozone. While looking around the oil section I noticed that the Castrol 0w-30 bottles looked old. Really old. I pulled one of the shelf and it was the American made fluid. There was about 15 bottles their so I started pulling bottles from the back and score I found some German Castrol. Anyways this stuff has to be at least 5 years old. Does anyone know how to identify when it was manufactured?