Does it matter if the production dates of car windows are different?

[PrestonLee]

It does not matter if the production dates of car windows are different. In fact, during vehicle assembly, it is common for the production dates of glass to be inconsistent. The vehicle factory is an assembly plant, and parts are stocked in advance for some time. It is impossible to ensure that every part is assembled immediately, so synchronization in timing is difficult to achieve. Additionally, different batches of glass naturally have different production dates, and this situation does not indicate that the vehicle has been involved in an accident or has other issues. There is a code in the lower left or right corner of the car window glass. In the last or second-to-last row, there is a number and a few small black dots, which represent the production date of the glass. The number indicates the production year of the glass, representing the last digit of the year, and the small black dots indicate the production month of the glass.

[SanThomas]

I've also pondered this issue before, and a seasoned auto repair master later told me there's absolutely no need to worry. Car manufacturers procure glass in batches, and it's perfectly normal for production to span different months. As long as the glass itself is OEM-certified and undergoes strict quality inspections during installation—meeting national standards for key indicators like thickness, light transmittance, and impact resistance—it's fine. Instead, he suggested paying attention to certification marks in the corners of the glass, such as the code starting with 'DOT,' which is far more important than the production date. If you really want to nitpick, there might be a slight 0.5% difference in UV blocking rates between glasses produced on different dates, but in actual driving, you wouldn't even notice it.