Calcium compounds are widely used. There are vast deposits of limestone (calcium carbonate) used directly as a building stone and indirectly for cement. When limestone is heated in kilns it gives off carbon dioxide gas leaving behind quicklime (calcium oxide).
How to Change Transmission Fluid. Transmission fluid needs to be changed from time to time in order to extend the life of the transmission, usually every 30,000â60,000 miles (48,000â97,000 km) (sometimes more â check your owner's manual for service intervals).
Most manufactuerers say the automatic transmission fluid will last over 100,000 miles with average use. But severe service rquires fluid changes every two years or 24,000 miles. Severe service can mean extended high speed driving, trailer towing, or just driving normally in cold weather. Some manufactureres (like Subaru) state that under severe  conditions you should change the AT fluid and filter every 15,000 miles. If the fluid is bright red and smells sweet, it is pobably still usable. If the fluid color is dark red or brown and smells burnt, change it.