Restore, not renew, discoloured headlights

Posted on February 19th, 2016 by Rob Marshall


Since glass headlight lenses were replaced with plastic covers, they have become more inclined to discolour and age. While glass would last indefinitely, unless shattered by an errant stone, or unstuck from the headlamp casing, the sun’s ultra-violet rays and chemicals from screen wash additives cause the plastic covers to degrade.

The problem leads to a loss of lighting efficiency. While cloudy lamps are an aesthetic compromise, they also reduce the effectiveness of both the lamp’s bulbs and reflectors. Yet, many owners tend to act after the problem is flagged-up at MoT Test time.

New lamps are expensive and costs can vary from £150 to over £1,000 – even more in the case of HID ‘Xenon’ units. Yet, obtaining even second-hand units can be pricey, especially after garage fitting and alignment fees are taken into account.

Over the past few years, headlamp renovation kits have been offered for sale, which permit an effective DIY repair that requires no special skills, other than the ability to operate a domestic high-speed drill. While I have had positive experience with a kit made by 3M several years ago, my latest attempt (conducted on a relative’s 2001 Renault Clio) was performed with a newly-launched product from Autoglym.

The procedure involves fitting a domestic drill with a special pad, to which various 800 and 1200-grit Velcro-backed sand paper discs are fitted. These remove the surface imperfections from the headlight’s plastic cover, to reveal the undamaged plastic beneath. Finally, polishing pads of 2,000 and 3,000 grit are provided, coupled with a special plastic polish. The result transformed a pair of discoloured lamps for an outlay of £22.99.

While I was pleased with the end result (my cousin was delighted), the procedure is time-consuming. Yet, although Autoglym’s kit is supplied with 800 grit sandpaper, I feel that very badly damaged plastic lamp covers require rougher grades, because it is easy to wear out all of the provided discs, before the bulk of the damaged plastic is removed. In the tested Clio’s case, I resorted to some 500-grit wet-and-dry paper (used without water and by hand) that I had in my garage stores, before switching to the kit’s 800 grit. Ample polishing solution was provided, however, and it is a nice touch that Autoglym provided a polishing cloth, which can be kept after the rest of the kit is redundant. Therefore, you have to ensure that you are sparing with the supplied sand paper discs, if you wish one kit to be sufficient for both headlamps.

You will also need to mask up any surrounding bodywork around the headlight, because it is easy for the spinning drill to slip and score the paint. While 3M’s kit provides a small roll of masking tape, this is omitted from Autoglym’s version.

GEM’s verdict – Autoglym Headlight Restorer

This is the well-established and respected Letchworth company’s version of kits that are available from other makers. While the product is nothing new, the illustrated instructions are concise and it works well. It is also priced competitively.

For future improvements, we would suggest that Autoglym includes a small roll of masking tape and further abrasive sanding discs, so that renovating a pair of deteriorated lamps is possible.