What could be the issue here? The engine is using up more coolant. It runs hot and would almost overheat. Also, whenever I restart the Dodge W250, the engine would miss.
It does sound like you're dealing with a coolant leak. The issue could stem from a bad head gasket or a cracked engine block. There could be water in oil, which could be blamed on a blown head gasket. The coolant may also escape into the cylinder instead of flowing into the vehicle's oil system. As coolant goes into one of the cylinders due to pressure while the engine is off, the engine may then miss when you restart the vehicle. This is because the coolant is flowing out into the exhaust, which explains why there could be steam coming out of the tailpipe. However, the steam doesn't necessarily indicate that you have a blown head gasket since moisture in the exhaust is quite normal, especially during a startup on a cold morning. To properly diagnose the problem, some tests should be performed to verify if there's indeed a bad gasket and coolant is leaking into the oil system or the cylinder.
Is the amount of refrigerant used for the car air-conditioning system the same for all vehicles? How much should be used when re-gassing the air-con?
It's not the same for all vehicles. The amount of refrigerant that should be used will vary according to make. This also varies per type of vehicle as well as per model and year. A full-size vehicle's air-conditioning system would typically require more refrigerant. The refrigerant is usually measured or metered through weight. To find out how much gas or refrigerant is needed, check the user manual.
What would be the best way to deal with an overheating vehicle? How should you respond to this untoward car situation?
Don't panic. Decelerate slowly as you pull over to the shoulder. You have to switch off your air-conditioning and then turn on the heater of the vehicle. As you pull over safely and find a good spot, turn off the engine. Allow the engine to cool down. Opening the hood will help. This may take a while, about 20 minutes for the hot engine to become cool. After the heat has subsided, check under the hood for the possible cause. The problem could have something to do with a faulty cooling system. See if there's enough coolant. Aside from the coolant, you may also check for a collapsed or cracked hose or a broken drive belt. The radiator could be leaking or clogged. As you inspect the vehicle's cooling system components. Be sure not to touch the radiator cap until you've killed the engine and have made sure that the top of the radiator is no longer hot. If you can't figure out the problem or would need to take the vehicle to the nearest auto shop, fill it up with more coolant and drive gently. If the vehicle simply runs hot quickly, the best course of action here is to call for some roadside assistance to prevent severe damage to the engine.