I present to you, a short but shite guide to headlight bulbs!
This thread has been in the making for over 3 years and has involved literally two purchases of uprated headlight bulbs and maybe an hour of eBay searching and a wander round Halfords. Why? Headlights have been getting steadily brighter over the last few decades. It's now getting way out of hand and we shiters are caught in an arms race of ridiculous brightness. DO NOT GET LEFT BEHIND, COMRADES. Your weak headlights will compromise you. We are driving cars with shit old headlights, but they can be better!
This will be obvious to many but it wasn't to me, so let me scribble down some musings in case it's of any use to anyone. I'm going to talk about foggy headlight lenses and then do a brief bit about uprated bulbs based on my extensive research on eBay and what I've read on more than one other forum. Please add your bits too.
Step 1, starting point - foggy plastic headlight lenses
Plastic headlight lenses degrade with age. From new they have a UV coating to protect the plastic from oxidising, which eventually breaks down and the plastic turns foggy on the outside. I absolutely recommend doing this and you'll be surprised what a difference it makes by polishing this off. Above, on the Mongda I've used a cloth and G3 rubbing compound and the difference is marked. By doing this you will immediately see more light coming out and your beam pattern will be restored. With the restored beam pattern, there is far less light scatter as it goes where it should do and I find I get fewer oncoming drivers flash me afterwards.
Unfortunately, once the original coating has gone, you'll have to maintain the lens by polishing it every couple of months. You can use dedicated products with UV protection which may be better but you will still have to look after them periodically. I've only ever used G3 and car wax and I re-do them maybe twice a year.
Step 2, uprated bulbs
There are some basics here:
The filaments in your bulbs are in a specific position so that the light reflects out to a specific place with a specific pattern. The more accurately the filaments are positioned inside your bulbs, the better the light quality will be. Cheap Chinese bulbs will have the filaments chucked in and the light will go all over the shop. For good light, pay a bit more and stick with good quality bulbs.
Filaments degrade with age. If you compare an old bulb with a new one, you'll see the older filament is covered with spiky bits and melted looking bits. Just having a new bulb makes a difference.
There is a standard minimum light output for bulbs. This is what the +100%, +130% figures refer to.
Based on the above. Avoid cheap bulbs. Anything claiming +ONE MILLION PERCENT ULTRA ZENON BLUE LEGAL FOR USE IN UK ECT for £3.67 for 5 delivered is going to be a shit bulb and the light will be bright blue and go everywhere. It'll probably be worse than your original bulb. Slightly related to this, because the filament position is so critical, it's difficult to see how an LED replacement bulb with an array of LEDS is going be able to emit the light output in the correct place. My personal opinion is these products aren't ready yet as a direct bulb replacement.
There are an array of good quality branded uprated bulbs. Philips, GE and Osram are some examples. These currently range from +100% to +150% light output and, using a 60/55W H4 bulb as an example, cost is around £15-£25 per pair delivered online. They are far cheaper online than in Halfords, where the markup is massive. Uprated bulbs are whiter in colour, but should not be blue. The light colour should be a good quality white. This is something to watch out for, because the colour range (temperature) is regulated and too blue is illegal in the UK. For example, the Philips Diamond Vision are too blue/white (colour temperature is 5000K) and do not comply with the regulations - but this is clearly stated so that you won't get caught out.
Upgrade 1: Autumn 2016. The car had standard H4 halogen bulbs when I got it and the light output was very dim and orange. This was a couple of years ago now, I didn't know what I was looking at so I went for some basic Halfords +100% uprated bulbs. A good quality looking bulb with a slight blue tint around the glass, as they all seem to have. These were noticeably brighter than the originals and the light output whiter and looked clearer on the road. They made a big difference on unlit lanes compared to the originals. They lasted nearly 3 winters over 40K miles in daily use, which I thought was fair. Overall: would recommend if you can't get access to buy anything online. Price: £15.90 each so they work out quite expensive compared to buying online.
Upgrade 2: Winter 2019. One of those burned out a few weeks ago and I went online this time. I wanted to give one of the increased output bulbs a go this time. Obviously had already eliminated the Philips Diamond Vision due to colour. Toss up between the Osram Night Breaker Laser, the slightly more expensive Osram Night Breaker Laser Next Generation, GE Megalight Ultra and Philips Xtreme Vision. There really didn't look like much between these, the specs and prices were so similar it was difficult to choose. I went for the slightly more expensive Osram Night Breaker Laser Next Generation, which had a little more brightness than the other Osram bulb and without the illegal colour penalty of the Philips Diamond Vision. £20.25 delivered for the pair. I've got to say I'm very impressed. The beam pattern is absolutely sharp as a knife, which I was not expecting. Light output is definitely increased on the road in front and improved on the left hand side, so the bank on an unlit lane is far more visible. Colour is a full rich white. Again, I did not expect this and assumed it would be much bluer in colour but it is not. High beam is good, though I don't tend to use it much, but a lot of light remains on the road and not up in the trees and sky, which is a good thing. Overall: at this point, definitely recommend. Only thing I can't comment on at this point is longevity. I would expect the trade-off is that the bulb is not going to last as long. It's burning hotter and is probably more fragile as a result. Only time will tell and I'll check back in when one pops.