Dif Locks are usually only put on vehicles that are going to encounter slippery conditions for the majority of their working life due to cost and added complexity. A better alternative in the current weather would be to make the fitting of winter tyres compulsory when the temperature is expected to be below 5 degrees centigrade for a prolonged period. Standard tyres are built to last, the downside of this is that the compounds used become hard at low temperatures causing the tyre to be less effective. Winter tyres are made of different compounds, so stay flexible and give greater grip in cold conditions, they are not just for use in snow as most people think.