One of my brake lights burned out recently and when I went to replace it, I was stunned at how many different varieties of bulbs there were. There had to be over fifty different types at the auto parts store. Just bare bulbs, not headlights or anything fancy like that. And each had their own number (using God knows what numbering system). Is there any point to this? I can understand needing ones of varying brightness, but that alone can’t possibly explain it.
Welcome to my world. Autoparts counterperson. Twelve years selling, six more as a mechanic. There is, at least in my eyes, no ryme or reason to most parts numbering systems. One small consolation is to be found in the lighting area. Strange but true. A headlight 9004 is the same in Wagner, Sylvainia, ACDelco. Same across the line. The same is not to be said of items such as filters where a Fram PH8A equals a Wix 51515 or an ACDelco PF20 or a Motorcraft FL1A. I do like my job but parts proliferation and longer lasting cars make it harder each day. Lets not talk about customers who have no idea how to answer your questions.
On a common car, you have one set of headlights for integrated brights or two for non-integrated. You have your parking lights, your hazard/blinkers, your fog lights, your reverse lights, your brake lights, your third brake lights, your dome lights, your courtesy lights, your door lights, your dash lights, your ash tray light, your under-hood light, your trunk light, and your storage console light. There are different wattages needed for each. A 55w fog-light bulb is too strong to be used for a dome light, and a 15w dome light bulb is too weak to be used as a marker light. In addition, the average store stocks lights from about twenty different manufacturers covering about fifty different years.
And you ask why they need all the bulbs! 
–Tim
P.S. The standardization of bulb numbers is because they are replacements using the OEM designations. The OEM bulb number will be printed in yellow, green, blue, or black letters on the collar. Take the bad bulb out and bring it in with you to match the OEM number.
Variations between the same kinds of replacement parts helps generate more revenue for the same company that sold you the item in the first place. Having worked in a wonderful world of consumer electronics service, I can say this with some certainty.
When a car (or CD player, or whatever) is sold, the manufacturer hasn’t seen the last of your money. They see a little bit (sometimes a lot) more of it a few years later when it comes time for repairs. There is a huge amount of money to be made in parts sales.
This works best if you hold a significant stake in the market share. Sony manufactures most of their own major parts for the consumer items they sell. If you are the proud owner of a Sony CD player, and your optical assembly needs replacement, you become essentially a repeat customer, even if it’s only for parts.
Matsushita will attempt to make their optical housings different from Sony’s so that when your Panasonic CD player needs parts, you go to them to spend some more money.
Smaller companies that buy sub-assemblies from competing manufacturers to make their own devices tend to go out of business sooner or at least make a lot less money because (my guess) (1) part of their capital goes to the OEM to build the product in the first place, and (2) when parts are needed, the OEM (not the original vendor) makes more money on the replacement parts.
Case in point: Crown & Carver[sup]1[/sup]. Both made cheap CD players using mostly parts from the big boys Sony & Matsushita (they bought the OEM’s entire transport assemblies & built CD players around them). Crown is now out of business, and Carver has dropped their low priced el-cheapo line of consumer electronics after filing for bankrupcy in 1999. Not the only reason, to be sure, but I’m sure it didn’t help.
So if you happen to become a major (or even medium-sized) player in any business where you sell something that people will eventually need parts for, make sure they come back to you for your parts. How do you do this? Make your parts different from those of your competition.
[sup]1[/sup] [sub]Carver also makes their own OEM parts for their line of high-end consumer items. This part of the business is, I believe, performing decently.[/sub]
Thing is though, Att, these bulbs are all aftermarket. No one buys OEM bulbs. They just buy bulbs that match the OEM designation. OEM bulbs are only available from the dealership and cost like $20 or some other extremely unreasonable amount.
Ignoring the circumstances of the post, however, it is solid.
–Tim
Attrayant’s statment is true but I would amend it to say that having the customer come back for parts makes money for the distributors. And profitable distributors helps the bottom line of the company.
Yes Homer, most people just go to Generic Auto Store to get bulbs. But the companies spend ad dollars to also build brand name confidence and this is a brand name conscience society. Just note the next t-shirt you see.
It’s those so and so engineers. The same ones who make you take an engine part way out to change a spark plug. First they say this is what next years model will look like. Then they get down to just how those tail lights will be mounted and hence manufactured. Now the nitty gritty of which type of bulb will fit this new tail light. Then they call the lamp makers and say they need a x mount with n lumens brightness.