Winter car care

Why is winter so brutal on our cars?

In a nutshell, road salt. Ever since the 1930s, road salt has been used extensively during the winter months in the UK to lower the freezing point of moisture on road surfaces, thus helping to prevent lethal ice from forming and causing existing snow and ice to melt. Indeed, given the instant mobility demands of modern day drivers and the fact that relatively few people would ever consider fitting winter tyres, road salt remains a cost effective option for managing road safety. However, road salt is far less welcome from the point of view of motoring enthusiasts and the wider environment in terms of the long-term damage it causes to cars and man-made structures; salt deposits tend to harbour moisture and vastly accelerate metal corrosion processes.

Why is road salt so damaging to cars?

Technically speaking, road salt is hygroscopic in nature, which means that it attracts, absorbs and retains moisture wherever it is deposited. Road salt accumulation on vehicle surfaces is therefore highly undesirable, since dampness is known to accelerate electrochemical oxidation, i.e. the rusting of iron containing metal components. In a nutshell, whenever iron comes into contact with water in the presence of air, oxygen is liberated from the water and then used to break down the iron into iron oxides (which are typically red or orange in colour, hence the term rust). Modern factory applied paint systems offer excellent protection against rusting, but once treated surfaces are breached by surface weathering or stone chip damage, corrosion can quickly set in. Suspension assemblies, brake components, steering systems, drive trains and sub-frames are all highly susceptible to this type of corrosion.

In addition to its hygroscopic nature, dissolved road salt also transforms water into a highly effective electrolyte, which not only accelerates the speed of rusting, but also enables galvanic corrosion to occur. Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially when in electrical contact with a different type of metal. In order for galvanic corrosion to occur, both an electrically conductive path and an ionically conductive path are necessary. This effects a galvanic couple where the more active metal corrodes at an accelerated rate and the more noble metal corrodes at a retarded rate. On cars, this type of corrosion is most common on alloy wheels with stone chip or kerbing damage, as iron-rich brake dust sitting on the damaged rim surface initiates more rapid corrosion of the aluminium alloy making up the wheel beneath. In the presence of road salt, such corrosion can proceed very quickly indeed.

How can I better protect my car against road salt?

Over the last twenty years manufacturers have invested heavily in improved multi-layer paint systems that are now much better able to withstand environmental stresses and the damaging effects of road salt; corrosion warranties now typically extend to twelve years or more, and it is uncommon to see cars with visibly rusting bodywork on the road. However, if you take a closer look at the underside of most cars, you will typically find evidence of fairly widespread surface corrosion, particularly on suspension assemblies, brake components, steering systems and the sub-frame itself. This arises because such surfaces are highly susceptible to surface damage from stones and road debris, and once protective paint coatings are breached surface corrosion quickly sets in. In order to properly protect our cars, we should therefore remember to care not only for the bodywork and wheels, but also for exposed surfaces in wheel arches and beneath the car as well.

Starting with the bodywork, in most cases a late autumn application of either Extra Gloss Protection (a high quality synthetic polymer sealant) or High Definition Wax (a high quality wax) will be sufficient to protect the paint system properly through the winter months; modern paint systems are very advanced and able to withstand environmental stresses very well on their own. The only caveat is that care should be taken to perform stone chip repairs as soon as possible after they are noticed, otherwise localised corrosion can set in. Various options exist with regard to making stone chip repairs, ranging from simple do it yourself touching in through to employing bodyshop services to respray the affected panel. Whichever option you choose, act quickly to repair penetrating damage, or at the very least make sure you apply sealant or wax protection as soon as possible – maintaining a barrier against moisture is critical in terms of corrosion prevention.


Moving on to your wheels, I can't stress enough how important it is to clean your wheels regularly throughout the winter months; preferably at least once a week using a non aggressive wheel cleaner. It doesn't matter how hard it is raining or how cold it is, just get your coat on and give your wheels a quick wash and don't worry about drying them off; just make sure you remove all of the brake dust and road salt. It only takes a few weeks for galvanic corrosion to set in on damaged rims crusted with brake dust and road salt, and in the winter many weekends can pass by without a single nice day, so avoid procrastination at all costs. We recommend spending a full day removing, cleaning and protecting your wheels prior to the onset of the first frost.

Don't worry we can do all of this for you, please call 07973122243 or contact us here.