Questions for master YMH and master YUE

[DayInDayOUt]

My car is 11 year old 2.3L Oldsmobile Archiva.
Recently I noticed the engine shaking so heavily and I can only get very low power from it.
I had a garage checked the problem and found out the ignition coils were not in good working order.
One coil was malfunction and other was half way there.
I had both of them replaced and the problem is gone.
So I have several questions.
1. Is it very common problem on the old vehicles or it's just bad luck?
2. If there's any preventive method I can take to have them last longer?
3. I guess the short circuit could be the major reason to damage the coil, so how can I check for the short circuit ? BTW, the coil unit is installed under the engine's top cover so there're no standard spark plug wires. It uses spark plug connectors instead.
Thanks.

 

[月下独酌]

it's a common problems in old cars, especially those ones that uses a distributor
those coils are high voltage coils with carbon as the conductor inside. overtime the external insulator breaks down and the high voltage leaks out, reducing your spark quality
but usually good coils last pretty long....
don't worry about it. they'll last til when you sell your car

but if you want to check the coil, spray some water on it and if you see blue light, that's a leaking coil