Originally Posted by mattliston

silverstars will work for him, he already has them, so why would he buy another brand? Ive never even heard of philips or osram for bulbs

Originally Posted by CandlePowerInc.com

H4, HB2, and 9003 bulbs
9003 and HB2 are different names for the same bulb, so these numbers apply to just two kinds of bulb: H4 and 9003/HB2.

9003 and H4 bulbs look alike, fit in all the same headlamps, have the same wattage rating and seem to be completely interchangeable, but in some places, the law says that only one or the other type must be used.

In 1971, the H4 bulb was introduced in Europe as the world's first halogen headlamp bulb that could produce both low and high beam from a single bulb. It quickly became the world's most popular headlight bulb except in the USA, where cars had to have sealed beam headlamps with non-replaceable bulbs. Motorcycles in the USA have never been required to use sealed beam headlamps, and so the H4 bulbs became popular for motorcycles in the US and worldwide. It is widely used to this day.

In 1983, the US Department of Transportation (DOT) first permitted cars in the US to use non-sealed-beam headlamps with replaceable bulbs, but DOT requirements differ from those in force outside the USA. On of the US requirement is that the beam aim must not change when the bulb is replaced. This can happen is a low quality replacement bulb is installed, because in a poorly made bulbs, the filament is often improperly positioned. Headlamps are optical instruments, and they depend on the filament being very precisely placed. If the filament is not precisely where it's meant to be, the beam pattern will be shifted or changed.

Like all engineered products, headlight bulbs are built to a technical standard which specifies all mechanical, electrical and dimensional aspects of the bulb. This blueprint makes sure all bulbs of a given type are interchangeable, and provides allowable ranges, or manufacturing tolerances, for each aspect.

In 1991, automakers wanted to use H4 headlights bulbs on cars in the US, but the DOT decided engineering blueprints for H4 bulbs allow too much variance in the position of the filaments within the bulb. So a new blueprint was made, with all the electrical and dimensional properties the same, but with stricter limits on filament placement variance. Because of the limits in the US on beam intensity in effect in 1991, the maximum allowable light output tolerance was also reduced. This new bulb specification was called "9003/HB2", because at the time, two numbering conventions were in use. Many 9003/HB2 bulbs also carry the "H4" marking, and vice versa, because it is possible to meet the specifications in both blueprints at the same time. The first headlamps with 9003 bulbs were on 1992 model cars.

Filament placement variance is not a problem with high quality bulbs made by reputable companies. At Candlepower, we make sure all our bulbs are better than the law requires. Our filaments are all precision focused inside watch bulb to ensure a properly placed, properly formed beam in any headlamp. In areas where there is no legal preference for 9003 bulbs over H4 bulbs in cars, any Candlepower H4 or 9003 bulb can be used with confidence in any headlamp.

Technical bulletin:
H4, HB2, & 9003 bulbs.

Who may use HB2 or 9003 bulbs?
9003 or HB2 bulbs marked "DOT" may be used in the US and Canada in any car headlamp that is marked "DOT HB2," and in any motorcycle headlamp designed to take an H4, 9003 or HB2 bulb. They can also be used in any car headlamp designed to take an H4 bulb.

Who must use HB2 or 9003 bulbs?
Automakers must install only 9003/HB2 bulbs marked "DOT" in the USA in headlamps marked "DOT HB2." To make sure such headlamps remain in compliance with Federal standards in the USA, use only replacement 9003 or HB2 bulbs marked "DOT." This is especially important in areas where headlamp bulbs are checked for "DOT" markings as part of a state vehicle inspection program.

Who may use H4 bulbs?
H4 bulbs may be used in H4 headlamps, in any country where such headlamps are permitted on cars or motorcycles. Outside the USA, thy may be used in headlamps designed to take HB2/9003 bulbs in areas where there is no requirement or inspection for bulbs marked "DOT."

Who must use H4 bulbs?
H4 bulbs with a circle-E mark are required in many countries outside of North America.

Copyright 2003 Candlepower Inc.

Originally Posted by NOFX

Oh, and I've had SilverStars last up to two years without a problem. It does not seem to be the norm though.

Originally Posted by NACvicSi

Nope, taken from manufactures website:

http://www.sylvania.com/LearnLightin...Lighting/FAQs/

Q) How long do the headlights last?
A) The life of any halogen bulb varies based on vehicle type, vehicle voltage, amount of time the bulb is on, road conditions, proper installation, and correct application. The average life of SilverStar® headlights is approximately one year.

Q) When is a good time to change my headlights?
A) SYLVANIA recommends evaluating you headlights once a year for optimum performance.

Originally Posted by Daniel Stern

Thinking of converting to HID?

So you've read about HID headlamps and have it in mind to convert your car. A few mouse clicks on the web, and you've found a couple of outfits offering to sell you a "conversion" that will fit any car with a given type of halogen bulb. STOP! Put away that credit card.

...

The most dangerous part of the attempt to "retrofit" Xenon headlamps is that sometimes you get a deceptive and illusory "improvement" in the performance of the headlamp. The performance of the headlamp is perceived to be "better" because of the much higher level of foreground lighting (on the road immediately in front of the car). However, the beam patterns produced by this kind of "conversion" virtually always give less distance light, and often an alarming lack of light where there's meant to be a relative maximum in light intensity. The result is the illusion that you can see better than you actually can, and that's not safe.

It's tricky to judge headlamp beam performance without a lot of knowledge, a lot of training and a lot of special equipment, because subjective perceptions are very misleading. Having a lot of strong light in the foreground, that is on the road close to the car and out to the sides, is very comforting and reliably produces a strong impression of "good headlights". The problem is that not only is foreground lighting of decidedly secondary importance when travelling much above 30 mph, but having a very strong pool of light close to the car causes your pupils to close down, worsening your distance vision...all the while giving you this false sense of security. This is to say nothing of the massive amounts of glare to other road users and backdazzle to you, the driver, that results from these "retrofits".

Originally Posted by NOFX

So by "nope", you're agreeing with me?

Mine lasted for about two years. I've had many customers who have had them last only a few months though.

Originally Posted by NACvicSi

Yeah I was agreeing it isn't the norm.

Originally Posted by DeSchlong

An excellent counter-point made about bulb life, but if you are considering an HID retrofit as some posters mention, I suggest reading here.

An excerpt:

Originally Posted by NACvicSi

HID's FTW. When you start adding up your bulb cost (friends Silverstars lasted 8 months) HID's aren't that expensive.