Is the loss of coolant sudden, or is it just a slow natural usage over time, due to minor leaks, evaporation etc.? First thing is to top it up with coolant and look for leaks or abnormal usage. i.e. Don't flush and refill with fresh coolant until you know the system is sound.my '10 lx says low coolant, so i wonder if a drain and fill or a flush is recommended? or does it matter? i know a flush can ruin the engine, i have almost 40,000 miles on it.