It might be reasonable to assume that the markings indicate oil fill date, but it could also represent the date in which the plastic bottle was manufactured. These days, they use this information to determine if a batch of containers was manufactured with a defect and to track them down if there was something wrong with it after distribution. Whether or not the filling date coincides with the container manufacture date may be arguable. It's probably safe to use the synth that you bought though.

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2000 Z3 2.3 Steel Gray
2004 X5 4.4i Jet Black