OEM (original equipment manufactured) and OES (original equipment supplied) many times are one and the same. OE, of course, is a more generic term that refers to the brand that came as original equipment on the car. Most auto manufacturers assemble cars from purchased components and manufacture only the sheet metal components.

Therefore, the "factory part" you can buy from your Volvo dealer was most likely made by another company, sold to Volvo and then resold to the dealer for ultimate sale to you.

An important point many people are unaware of is the fact that multiple OES brands are not only normal but are actually mandated by international standards as part of the qualifications for ISO certification. Car manufacturers must have secondary sourcing (i.e., multiple suppliers) for certain types of parts in order that any problems with one supplier will not disable the car manufacturer's production and allow for substitution of the other brand for new production and any warranty replacement or repairs.

Often many OEM/OES companies stock the exact same parts as your local Volvo dealer - usually at substantially lower prices! It may not always come in a package with Volvo’s name but it is, in fact, the very same part, manufactured by the very same company.

Why pay for all those middlemen when you can get the exact same part elsewhere. You're not skimping on quality - it's the same quality as the dealer's part. You're just cutting out the overhead caused by too many middlemen.

Volvo Dealer Only Parts
Often OEM and OES companies cannot release OE parts for "new" cars into the aftermarket (because of licensing agreements) until a few years have passed. This restriction allows the car maker to recoup tooling costs, build in repair revenues for the dealers and justify larger OEM production runs to keep costs down.

Although irritating that some parts are "dealer only", it's in your best interest for warranty purposes. As new car warranties get longer, the dealer must maintain cars that fail to perform for longer periods of time. So if you're driving a newer Volvo, you may need the dealer for a few more years on certain items.

OEM/OES vs. Aftermarket Parts
The true "aftermarket" part is one that's been copied from the OE part. In many cases, this is done to offer a lower cost alternative. But in most cases the benefit of the lower price is far outweighed by its major disadvantage - it's usually an inferior product and ends up costing you much more in the end in avoidable repairs.

There are, of course, exceptions to this rule as car makers try to reduce assembly costs by going to lower cost alternatives on parts that wear out and routine maintenance parts.

But, beware: Aftermarket parts stores - the big name mass merchandisers you find in every town - normally carry ONLY "aftermarket" copies of OE parts. It's the most cost-efficient way for them to compete on price with the thousands of other parts stores. Besides, most of their customers care more about price than performance anyway!