Seems with the release of batchs marked 05......., it will last for another year......maybe. A few folks (myself included) are sitting on the fence waiting for some UOAs with the 05 stuff. Recent VOA shows a slight formula change and it no longer has the deep green hue it once had. Castrol being the ever, uh, *dynamic* company it is, and with its recent purchase by BP (2000?), it wouldn't surprise me if the internals have been tweaked. The cutting edge technology with its make up (esters) may have gone by the wayside due to cost or availablity. Or maybe they have sourced something different, who knows? Better or worse? We'll have to wait and see.