LED suggestions please

Hi, I am looking for suggestions for an LED that will work on a 12v DC system.  I want the LED to light up when a spark plug sparks so when the engine is running it will be on almost constantly but for development purposes I would like to use it as a signal for me.

I did buy some from eBay and they stopped working quite quickly and I'm just not sure what I should be looking for.

Thanks, Daniel.