Bought what I think is GC 0w30 gold for my 95 BMW. It is the "square" bottle, states made in germany and European formula on front. Serial number in white on bottom starts with M052876B.. which leads me to think it is gold. I think thii oil will be fine in my M50 BMW 6 cylinder engine with 134,000 miles. Does not use any oil between 4-5,000 mile oil changes. Been using 5w40 or 5w50 Castrol Syntec oil. I did not like Mobil 1 0w40 (noisy engine). Bit concerned that 0w30 oil may not be heavy enough as older BMWs tend to "enjoy" heavier oil. Any thoughts? TIA