Dear Art,

You're right about Bosch & Regina ECU rarely fails. When they fail you'll know it instantly if there's a spare available. Instead of doing a simple ECU swap, I see some owners throwing parts at the car, spending some $$ before finally coming back to the ECU. Of course this scenario rarely happens but who knows when it happens? (taking into context of old cars here).

Yes I'm convinced most (if not all) electrolytic capacitors with rubber plug at its base do age out. The quickest one that does lives inside our speedometer having exposed to lots of underdash heat. The ones with not so fast aging (about 20 to 30 years I suppose) lives inside our ECU. The only one that doesn't seem to age is the bakelite body electrolytic capacitor with epoxy sealed base in my hi-fi preamp made by Roederstein. But then the preamp has always been running cool. My point is capacitors in spare ECUs kept in cool (and dark?) places could maintain their value for much longer (even with same vintage).

Lastly I remember capacitors datasheet do give life estimation in hours. Anyway I should stop rambling about capacitors here, dinner's getting cold :-)

Regards,
Amarin.