1993 Honda Civic Owner's Manual - Page 115

Cooling System Checking the Engine Coolant Level RESERVE TANK Always use Genuine Honda Antifreeze/Coolant. The cooling system contains many aluminum components that can corrode if an improper antifreeze is used. Some antifreeze, even though labeled as safe for aluminum parts, may not provide adequate protection. Adding Engine Coolant If the reserve tank is completely empty, you should also check the coolant level in the radiator. MAX MIN Removing the radiator cap while the engine is hot can cause the coolant to spray out, seriously scalding you. Always let the engine and radiator cool down before removing the radiator cap. 1. Make sure the engine and radiator are cool. Check the level of the engine coolant by looking at the radiator reserve tank next to the air cleaner element box. If the level is at or below the MIN line, add coolant to bring it up to the MAX line. This coolant should always be a mixture of 50% antifreeze and 50% water. Never add straight antifreeze or plain water. Maintenance