When it comes to automotive glass, there are two main types: OEM (Original Equipment Manufacturer) and aftermarket. OEM glass is the original manufacturer's quality glass, the same one that would have been installed when your vehicle was new, and it even has the vehicle's brand logo. Aftermarket auto parts are manufactured by a company other than the original equipment manufacturer, or by the same OEM company on a different production line. Some of these parts are of similar quality to OEM parts.
If you have an older vehicle, such as a collector's car, repairing or replacing anything with OEM parts preserves the originality of the vehicle. Generally, insurance companies will only pay for OEM glass if the vehicle is less than 2 years old and is still under a full coverage policy. If you're paying for out-of-pocket glass replacement, aftermarket auto glass might be the cheapest option. A useful distinction to make when requesting quotes for automotive glass is between OEM glass and OEM quality glass.
If the original manufacturer uses that windshield a year later, it is likely that it will also be considered an OEM part, as long as it is produced in full detail using the original manufacturing process and machinery. Conversely, if another company also operates that same part to sell to automotive glass wholesalers and replacement stores, that part (no matter how well manufactured) is not an OEM part. Some purists might say that unless the part enters the vehicle on the assembly line, it cannot be an OEM part because anything that comes after the original part is installed is a replacement part. Others would say that, as long as the part used for the replacement was manufactured by the same company that manufactured the original part, it is in fact an OEM part.
Others go further and say that the replacement part would have to be manufactured by the same manufacturer, with exactly the same specifications on the same production line, at the same time as manufacturing OE glass parts to be considered equivalent. Just for the record, many non-OEM parts are as good as an OEM part. A term that has become prevalent and promoted by some is the term OEE (Equivalent to Original Equipment). This term makes sense to me, but then it becomes a question of “equivalent to what standard”? Who determines if the part is truly equivalent? There is no clear answer. There are poor imitations that should not be considered for use in a vehicle.
Deal with reputable providers and people you can trust. Since your windshield supports the structural integrity of your vehicle, especially in a rollover situation, it is definitely a safety-related part. If you are driving a vehicle equipped with ADAS features (Adaptive Cruise Control, Automatic Pre-Collision Braking, Lane Change Warning and Roll Warning), it may be wise to consider OEM glass. This will help ensure that the sensors and cameras associated with these systems have a clear view of the road, which will allow these systems to work properly. Companies that manufacture OEM and aftermarket glass, some that offer products to both markets, are cautious in taking a position. Another industry veteran, Russ Corsi, who worked with PPG (a manufacturer and manufacturer of automotive glass) for many years, points out that OEM products often have very strict inspection criteria and very tight tolerances. Corsi also noted that some large glass manufacturers make OEM and aftermarket products, so they have more tools in the arsenal to make their products quite similar in both markets.
Automotive glass plays an important role in vehicle safety by providing structural rigidity, eye clarity and “integration” with advanced vehicle technology. In conclusion, there may be some brands of auto glass which are different from each other but this doesn't really make any difference when it comes to safety or performance. If you're paying for out-of-pocket glass replacement, aftermarket auto glass might be the cheapest option but if you're driving a vehicle equipped with ADAS features it may be wise to consider OEM glass.