fireclown said:
1) At what point does diesel gel?
Cool answered. Due to winterizing, the cloud and gel points will drop in local fuels.
fireclown said:
2) How does a glow plug work, and at what point will it not help me?
A glow plug resembles (somewhat) a longer extended spark plug. The tip has no gap; instead it has a closed end metal extension that has heating coils inside. Somewhere on this site is at least one photo of a glowplug on a bench where you can see the tip end glowing red.
The heat created helps the fuel vaporize and then burn on a cold morning. It needs this until the engine generates enough heat internally to run smoothly. Until the engine is warmed up, and if the air temps are very cold, you are likely to see white or gray smoke to varying degrees frorm the exhaust. Sniffing this smoke will smell of raw fuel, because it is the heavier components of the diesel that did not burn in the cylinder. As soon and the engine warms up some, the smoke goes away.
fireclown said:
3) Do you use an engine warmer?
I used to, when I had a garage in which I could plug it in. I use an oil pan heater, not made by VW. That was when I lived in Salt Lake City, and there were winter mornings when it made things much easier on the starter.
fireclown said:
4) What fuel additive should I use to pretreat a tank of fuel? Which should I carry with me to save my butt if it gets freaky cold overnight by surprise?...
I use winterized Redline. They have 2 types available, one winterized and one not. I bought a case of the winterized type, and use it year round.
As zocco said, there is one additive that is possibly the overwhelming favorite. I don't think it is due to empirical testing that has shown any particular quality beyond that found elsewhere. I made my choice due to lackluster lubricity testing results in the Spicer study. Even so, carrying some 911 would be cheap insurance if you like to worry. But the best results will be had by treating before, and not after, a gelling problem happens.
I've only had gelled fuel once, and I think it was because I got inadequately winterized diesel and carried it for at least a couple of months (I've a short commute) and then we had a record cold morning (-27F) that morning. But it is a short commute - I just walked and was a bit late that day.
If you're running from cool to very cold on a trip, the best way to prevent gelling during an overnight cold soak is to have very little to no fuel on arrival, and fill up at a local station. Then drive it around for 10 minutes, and you should be OK.