One of the spare parts that a BMW 2002 owner should carry is the oil pressure sender switch.
Located at the back of the engine on fours next to the distributor, it can crack. And when the oil pressure sender switch does crack, oil is forced out under such pressure that the engine's oil will very rapidly be gone.
This $3 part can save you a long walk, tow charges, perhaps even an engine. When buying a spare switch, carefully remove the one you have to find out whether it has coarse or fine threads. Reinstall just as carefully. One of these in the trunk would have saved me hitching on an interstate and buying oil at $2 a quart!
Author: Jim Brady