Although many convertibles are now suitable for winter driving, the majority of convertible owners limit their use to the warmer months. Owners of vintage and classic cars prefer to protect their treasures from the adverse effects of winter weather and road grit and salt. But these precious vehicles should not simply be garaged without further ado. "A few simple precautions and actions will ensure the car is fit for the road again in spring", says Eberhard Lang, TÜV SÜD’s expert.
Taking up position: Summer cars are best stored in a dry, well-ventilated garage. If the vehicle has to survive the winter in the open air, it should at least be parked on a firm, smooth surface. Parking spaces with permeable concrete pavements are death to tyres! They may cause permanent deformation of the tyre footprint, while grass or plant residues will damage the rubber compound during long periods of standing.
Water way to go: Thorough cleaning will help to prevent rust and starting problems in the spring. Don’t forget to include the underbody and the engine in the process! But be careful when using high-pressure cleaning equipment and keep a minimum distance of 50 centimetres to units such as the alternator and other electrical components. This also applies to tyres. "A high-pressure jet of water may cause permanent damage that may not be visible at first", points out Lang.
Oil change: Fresh oil protects the engine. "When the car is driven, acids and other aggressive substances that attack metal parts and seals develop in the oil", says TÜV SÜD’s Eberhard Lang. New oil is still relatively free from these destructive substances. But be sure to buy the right kind! Many new cars use special synthetic oil and lubricant types that are unsuitable for genuine classic cars. The car manual will give details of the correct types for the vehicle, and information can also be found by asking at garages or checking the websites of the oil manufacturers. By checking the oil levels in the transmission, differential and power steering system and topping up where required, you can ensure that all cogs and bearings are optimally supplied during winter hibernation.
Letting the air in: Moisture causes corrosion and unpleasant odours, and dirt is the ideal breeding-ground for both. Thorough cleaning of the passenger compartment prevents this problem, while ventilation creates healthy conditions. Simply open the side windows a few inches for ventilation. Pollen filters should be removed in winter if possible; not only are they a potential source of mould, but modern active charcoal filters also absorb water and are then unusable in spring.
Fully charged: In genuine classic cars, the battery can be disconnected. However, in modern vehicles that contain a lot of electronics the battery should remain powered up – preferably hooked up to a modern electronic battery tender, a charger that automatically tests the charging level and only charges the battery when needed. This ensures the battery is always at the optimum charging level without the need for the driver to take action. Drivers that ignore this point may be faced with expensive consequences. "A dead battery will freeze when temperatures plunge, and in the worst case will leak sulphuric acid when a thaw sets in", warns Lang. Compared to older battery chargers, these smart devices use very little energy. If the vehicle parking space has no power point handy for a battery tender, drivers are advised to charge the battery at monthly intervals as a minimum.
Putting on the pressure: A slightly elevated inflation pressure is best for the tyres. Tyres lose air over the winter, so that around 0.5 bar over the normal level is a good idea. "But no more than that", warns the TÜV SÜD expert.
Caring for the convertible top: Car manufacturers sell special detergents and preservatives that will conserve the value of the textiles. However, modern synthetic seals do not require any special care products – cleaning with soap and water will be sufficient. For classic cars, talcum is the gold standard for the rubber parts of the top. The fabric top itself is best left in a relaxed position, i.e. slightly open, for garaging over the winter. Never leave the roof fully down over long periods, as this may cause permanent folds and areas of fatigue. Retractable hard tops do not require any special care.