What is seasonal maintenance? What are the contents

Seasonal maintenance is a kind of timely maintenance that is carried out when the seasonal temperature changes, and measures are taken to prevent the cold or reduce the temperature. Seasonal maintenance can be combined with regular maintenance or minor repairs, and is performed once a year around April and October. Use high viscosity lubricating oil in summer and low viscosity lubricating oil in winter; check and adjust the specific gravity of battery liquid; in winter, it is the railroad car to take anti-cold and anti-freezing measures for the engine cooling water