A car doesn't need to outright shut down when you're on the road for it to need urgent car servicing; there are many telltale signs of needed repairs that a car owner would do well to learn to ensure the vehicle is repaired as soon as necessary. This will keep you safe on the road, help to avoid even larger repair bills in the future, and will also help to avoid excessive wear and tear on many of the parts under the car's hood.
If you have the car's oil changed on the schedule recommended in the owner's manual, there should never be a reason for the oil light to come on. If the oil light comes on, and especially if it comes on repeatedly, this often means the car has an oil leak, and this is very dangerous for the engine. Oil lubricates and also cools the engine; driving with low oil levels, especially if you do this repeatedly, can cause wear and stress on the pistons and other parts under the hood, and the engine can actually seize up. Add oil and then have the car serviced as soon as the oil light comes on to let your mechanic check for leaks.
Your car should never make a clunking sound, as this noise usually means something has broken loose and is now hitting something else under the hood. To help your mechanic, try to note where and when you hear the sound. If you hear it when you hit a bump and it's in the area of the wheels, this often means a broken shock or spring; if you hit a bump and hear the clunk in another area, this can mean any number of metal parts along the exhaust system or steering have broken. If the car clunks when you put it in drive, this often means a problem with the transmission.
Never overlook consistent stalling; this can mean that the catalytic converter is clogged, so that oxygen gets stuck in the engine, causing it to stall. The fuel pump may also be failing, so the engine is not getting enough fuel. The car's timing may also need adjusting; this system controls the timing of how the pistons move up and down, in synch with one another. All of these problems put added stress on the car's engine, and all can eventually lead to the engine shutting down altogether. Have persistent stalling checked as soon as possible, to avoid further damage to the engine.