This document discusses fuel additives and when they are needed or not needed. It states that fuel additives are available for petrol and diesel engines in India and are made by companies like Chevron and 3M. The primary functions of additives are to clean fuel injectors, reduce exhaust gases, and prevent corrosion. Additives can boost performance and efficiency while extending engine life. Additives may be needed in extreme hot or cold weather, especially anti-gel additives for diesel in cold weather. Additives can also be used when a vehicle will be idle for a long time to help it start smoothly. New vehicles generally do not need additives for the first 1-2 years, and additives should be avoided while a vehicle