I just wanted to post a good experience (if I can call it that)
Last year, my jetta would start on cold days without being plugged in (-15 Celsius was about as cold as it got in Kingston when unplugged). It would turn over slow, but eventually it would go.
This year, no such luck. I had problems when it was -10 C. I often needed a boost after work, which was kind of embarrassing (my battery would only crank for 30 seconds). I was hoping to squeeze through the rest of this winter, but after enough embarrassment, I bought a new battery. I bought a 'Motomaster 72' battery from Canadian Tire. It was their last one (manufactured Oct 2005), and I was skeptical to take it; but I was in a bind, so I did. The clerk was a real piece of work. I asked him if it was good, and he took the voltage across the battery. 11.98 V. That doesn't mean a whole lot...
Because, when I got stuck the next day, and tried to boost my dead battery off the 'new' battery, I wouldn't even get a spark off the cables (and a very weak spark from shorting the cables for a split second). The Queen's University parking attendant tried to help me out, and offered me a boost. It was about -25 C. We tried for about
1/2 an hour, letting the battery charge for 5 - 10 minutes each time. Nothing. Just cranking.
The parking attendant was kind enough not to give me a ticket on my illegally parked car for the day. I tried getting a boost when it was only -20 C that day. Again nothing.
I took the 'new' battery in, charged it up, and started it on the next
-13 C day. It cranked for a long time before firing, and after firing, took another 10 seconds to get up to running speed.
I guess only about 1 or 2 of my glow plugs were working.
At work the next day, I plugged it in (-25 C). Didn't matter -- STILL wouldn't start. I was steaming mad. I took the bus home and picked up 4 new Bosch glow plugs ($20 /each at canadian tire) on the way in the next day. Tried to change them myself at lunch (I only have a few wrenches...). I got one done (approximately 1 hour), and that was a hassle and a half at -25 C (the terminal broke off one, and I had to clamp a vice grip on it to wrench off the rusty nut). I didn't have another 4 hours to finish, and the one I changed was the easiest to access on the driver's side (so I wasn't looking forward to the other
3). The one plug was enough to start it though (painfully - cranked for about 30 seconds, and I had to push the choke in). I brought it to the mechanic, and they did it in about 1 hour for $70. Not bad.
I should have done that long ago, when the problem started.
Now, my car fires before you even hear a full crank at -15 to -20 C without being plugged in. It's amazing...
-Randy