It's that time of year when you may need to perform some maintenance on your car to keep it safe and give it the best protection through the winter.
In a road car, about 90% of the engine’s wear can occur during cold starts and this is only made worse with low winter temperatures.
The thicker an oil is when it's cold, the longer it takes to flow around the engine. The longer it takes for the oil to get where it's needed, the less protection the engine gets. That means that an oil that is thin when cold will give the best cold start protection, but it's not always practical to use a 0w or 5w oil. A worn engine can leak oil if it's too thin, whilst heavily modified forged builds have larger tolerances, meaning that the oil can get past the piston rings and burn (although this would probably only be a problem when cold).
But for the majority of cars manufactured within the last 20 years, you can use a 0w or 5w oil without any problems to help provide good cold start protection. With older cars, you can usually use a 10w rather than a 15w and a 15w instead of a 20w.
If a car needs a thick oil when hot (for example a SAE50), then using an oil that is very thin when cold (0w-50 or 5w-50) can be an issue. The large viscosity gap can make the oil unstable, leading it to break down to a thinner grade relatively quickly and rising oil consumption. With many cars, if they have two oil changes a year, it can be a good idea to use a thinner grade for the winter and a thicker one for the summer.
Another thing you can do to help protect your engine over the winter is to use an ester based oil. The ester content of the oil is electrostatically charged, which helps it to stick to metallic surfaces. That means there is already a layer of oil in place when you start the car up. If you have a track car that is stored for the winter and it's had an ester based oil in it for the summer season, leave the oil in there so the ester content helps to coat all the metal surfaces while it's out of use.
Heat pads are available to sit under the sump and warm the engine oil before use, but they aren't really necessary in the UK if the correct oil grade is used.
The main issue for gearbox oil is that if the oil is too thick, cold gear changes can be almost impossible in certain cars. In the UK it shouldn't get cold enough to need a much thinner than standard gear oil (although using something like a 75w-90 rather than 80w-90 will improve the cold flow rate), but in Northern Europe and other cold areas, some cars will benefit from using something thinner (MTF instead of 75w-90, ATF rather than MTF). A lot of people that use thick gearbox oil for competitive use in the summer find that cold gear changes are much more difficult in the winter and they may need to use a different oil.
Make sure that you have enough and that it's not over diluted. Last winter the temperatures dropped to below -20oC, so well below the freezing point of water, and that can cause real problems if there is insufficient antifreeze. As the water freezes, it expands and that can really damage the cooling system and engine if there is nowhere for the water to expand into.
As the temperatures drop, you may find that a diesel engine gets harder to start from cold. This is often due to glow plugs that need replacing. They might have been absolutely fine a month or two ago, but the lower temperatures of the last couple of weeks are likely to be low enough to show if the plugs need replacing.
Another problem with diesel is that it can freeze at -15C (dependant on the blend, as it's a mix of hydrocarbons, there is no exact point where all diesel freezes). Last year we spoke to several people who had tanks of diesel (mainly for agricultural and commercial purposes) that had frozen during the coldest nights. That left them stuck as they couldn't operate their vehicles with frozen diesel. There are a few fuel additives that can be mixed with diesel that lower the freezing point, down to -30C to -40C, meaning that it doesn't freeze in the UK.
Air Filters/Induction Kits
If you have a aftermarket cone-type filter or induction kit that is exposed to the elements or liable to pick up spray from the road, make sure it's properly cleaned and oiled. That should prevent excess water and debris from entering the engine, but if you want to really protect the filter, get a filter wrap to cover it.
Your windscreen is a very important part of your car and you want to keep it as clear as possible to be safe. Get a good de-icer and scraper for frosty mornings, some decent screen wash (in a more concentrated mix than in the summer) and a reliable set of wipers to keep it clear.
With salt being added to the road surfaces, it will spray onto your car's bodywork and can harm the finish. Give the car a wash and seal the surface with a good layer of wax or sealant. You can do the same to your alloys.
If you have any exposed metal or if you know if your car is liable to rust spots in certain areas (wheel arches, door sills etc), using a light oil spray to cover them is a good idea. It gives a little extra protection against the salt and water coming off the road.
- The team at Opie Oils