i went to autozone to buy 5 quarts of castrol syntec 0w-30 fully expecting to get 5 quarts of gold colored GC. all the bottles had the M05 number printed on the bottom and on my two previous visits at this autozone i found only gold GC. when i opened the cap i noticed that the oil was green. i thought i was using my personal stash of M04 GC on my brother's car until i doubled checked the number and it was M05. four out of the five M05 bottles were green while the other was gold. has this happened to anyone else?