[...] I would use a microcontroller to control the servo to turn the key to a predetermined angle to start the ignition, and return.
Like already mentioned by rbtying
, it wouldn't be the best way to do it with a servo, although they do come with much more torque than needed (at a fairly low price).
When you turn the key with thumb and index finger, you probably use less than 1kg-cm force (guessing here, haven't measured it) and the stronger standard servos comes in torque ranges several times that.
Installing a heater (electric or fuel) is how it's usually done (you pop one of the anti-freeze plugs and insert an immersion heater with the electric (mains driven) version and although I haven't seen an "oil burner" up close, I assume it's a similar setup. That way, starting isn't that hard on the engine, as it is already warmed up a bit.
To start the engine by remote (or timer), you need two "switches" (relay contacts or transistors), one to turn on the ignition and one to crank the engine (or rather to activate the starter) - just like the contacts on the ignition key switch.
To make sure it's starting, the controller just need feedback from eg. measuring when the RPM goes above what the starter can manage - when that happens, the starter should be shut off (but the ignition should stay on of course). It is necessary for the engine to be able to be running idle and if it dies down, it can be detected as well and a new start attempt can be made.
To avoid running down your battery (or worse - melting the windings in the starter motor), careful thought should be given to how long it is allowed to run in one go, or thermo sensors could be installed on the starter motors frame (if it can be done in a mechanically safe way), to keep the starter from hurting itself.
There should be a limit to the number of times it attempts to start, reasonably pauses built in and the condition of the battery should be monitored as well.
The "easy" way to make a remote starter is to sacrifice an old cell phone (if you can find one that works during the lowest temperatures you'll likely experience (perhaps a problem in Alaska during the cold season? In your pocket it's held at reasonable temperatures, but in a car shut down for 8 hours or more...).
A PMR or Walkie Talkie or dedicated transmitter and receiver could be used as well, as you're not likely to be that far from the car when you want to start it anyway.
Most cell phones can be set to use different ringtones, depending on the callers phone number, so can be set to eg. a pair (or even a sequence) of DTMF tones which can be decoded directly from the speaker wires (speaker could be disabled if wanted), via a DTMF decoder chip and fed into a controller for further checking and can then give prerecorded response if needed. Several phone numbers can be selected for this action - just give them the Open Sesame ring-tone. The "all (other) users" can just go to a silent ring tone.
That way, no other phones than those you select can be used to start the car - easy security.
Feedback, if needed, could be in voiced messages like: "Attempting start". "Engine running", "cabin temperature is now nn°", "Battery is now nn.nnV", "Scantilly clad blond female leaning on car", "Oh, it's just your wife who locked herself out trying to see who's starting the car", etc.
Your imagination (and the amount of complexity you are willing to add) is more or less the limit.
The problem I see happening is that sometimes it takes a little bit longer to start my truck than others on very cold mornings.
That won't be a problem when a controller is used, as already described.
That said... If you haven't done any electronics or microcontroller work at all previously, you're in for a steep learning curve, so you have to be certain that you're gonna reach the goal, or you'd just waste time and money that could else be directed towards a ready made engine heater.