First of all I don't use them as fog lights. I haven't seen fog here in 25 years, so, I use them as additional driving lights. The first thing I did was take the reflector'/lens unit out of the plastic housing so I could clean the lens from the inside. There is some sort of chalky white deposit that forms inside. I have no idea what it is. Unlike a popular Youtube video you do not need to cut the sealant and remove the lens from the reflector. It's a hassle and you have to use sealant to put it back together. An easier way which I discovered is to just remove the socket from the reflector. There are 3 tabs you need to bend back and the socket will come out. With the socket is that black shield which restricts your light beam. Just break it off. Now you have an access hole to the inside of the lens. Another Youtube video suggests rinsing the inside with Brakekleen. That doesn't work. Neither does using a bristle brush and Brakekleen. Acetone doesn't work either even with scrubbing. It was obvious to me then that the chalky deposit isn't organic, it must be a salt. Probably a base salt. So, I tried vinegar with scrubbing and it came right off. So, now it looks clear like new. I also replaced the standard Hella H3 bulb with a Hella 2.0 H3 bulb which claims to be up to 100% brighter over standard but is still 55w. Yeah, I know I could use a 100w or 130w but I'm not going to upgrade wiring or deal with excessive heat in the housing.
