At this time of this writing, I've owned my 7.3L diesel-powered Excursion for over 4 years and previously owned a 1997 F-250 HD with a Powerstroke in it as well. Over the years I've discovered some tips and hints that will help other diesel owners get the most out of their Powerstrokes during the colder times of year. I live in Minnesota where we can experience temperatures well below zero. These tips are more or less targeted towards the folks that can get snow in their area and will experience temperatures below freezing.
Plug it in if you don't drive it daily
I drive my Excursion nearly every day (to work on and weekends). With a nearly 70-mile round trip Monday-Friday each week and the typical weekend errands, the diesel gets a nice workout each day. My Excursion gets parked in my insulated (not heated) garage every evening and will spend the work week sitting outside on an open parking lot (exposed to the elements). At the time of this writing, I haven't plugged the block heater in on my Excursion in a couple years. What I've found is that if you drive your diesel every day, or nearly every day, and drive it along enough to get it to operating temperatures each time, it has a very easy time starting. However, if you let it sit outside in very, very cold temps (below 0F) without starting it, you run the risk of it not starting at all when it comes time to drive. If you are going to leave your Excursion sit for a weekend or longer in sub-zero temperatures, plug your block heater in. This will help keep the block warm and make for a much easier start when you need to drive.
Cycle the glow-plugs 2-3 times on really cold starts
What I've found works really well to get your Excursion started on an extremely cold day is to cycle the glow plugs 2-3 times. Follow these steps:
Insert key into ignition
Turn to the "wait to start" position
After the "wait to start" light turns off, turn the key to the "off" position"
Perform steps #2 and #3 three times, then start the Excursion
This has worked for me several times when the Excursion didn't start on the first or second try during a cold day.
Try starting 5 times, then quit
I've burned out a starter after trying to start a Powerstroke 9 times in a row. I mention "9" times because my remote starter will attempt to start the vehicle 3 times before quitting. I simply was trying to get the Powerstroke to start from the comfort of my house after it sat outside in sub-zero temperatures for an entire weekend (it was unplugged, too). After the 9th time, the starter managed to burn itself out.
Bottom line, 5 times is an arbitrary number, but keep that in the back of your mind as you attempt to start your Powerstroke. These things need a lot of cranking power to get started. If it hasn't started after 5 times, you're not going to get it started, so plug in the block heater, throw on a battery charger, and let her sit for an hour before trying again. Starters are expensive items to replace on a diesel ($400-500).
Parking lot strategies
On a very cold, windy day, never ever park on the end of a row of cars if you're parking in an open lot and will be exposed to the elements. Always park with a group of vehicles where your Excursion will be protected by these other vehicles. It's funny, but it will help you with cold-weather starts. This is particularly useful when parking at a store, mall, airport, etc. where you don't have access to an outlet for the block heater and will be leaving your Excursion for several hours (or days). A stiff wind on a sub-zero day will wreak havoc on any vehicle that is out in the open on a parking lot. By parking with a group of vehicles surrounding you, you reduce the possibilities for the elements to really have an effect on your Excursion.
Cold-weather fuel additives
As of this writing, I've been using the Amsoil Diesel Fuel Modifier. While we havne't had any severe cold temperatures yet for me to truly test this product, I can comment that it starts a lot quicker with this additive. Simply add 2 oz. per tankful of fuel.
Don't go lower than 1/4 tank of fuel
Since you never know how cold it can really get, don't find yourself stranded with a only a few drops of fuel left in your tank that end up gelling in cold temperatures. My rule of thumb is always to leave at least 1/4-tank full of diesel during the winter months. This at least provides a solid base of fuel in the tank so that even in the harshest of temperatures, I will still have enough fuel to help prevent diesel fuel gelling. Haven't had a problem yet!
Diesel #2 vs. Diesel #1 & Blended Fuels
You'll find that when you travel to other states that don't get the harsh cold temperatures, the "big rig" truck stops will provide a few different diesel fuel options. Always plan ahead for where you're driving to. I've gotten as high as 19 MPG in my Excursion, and that equates to over 800 miles on a tank of fuel. 800 miles can carry you quite a long ways away and into much colder temperatures if you haven't planned ahead. Always know where you're headed and what the temperatures will be, particularly during the winter time. The last thing you want is to have your fuel to begin gelling up in your tank.
Summer fuel. Don't run this during the winter time. Most gas stations will automatically switch their single diesel fuel pumps over to a blended #2 or a diesel #1 which includes a winter additive to prevent gelling.
Diesel #1 & Blended Fuels
Use these during the winter time. Do note that because of the additives in these fuels that your fuel economy will be lower.