Seriously, I always used the hot water mathod, or if one is available a heat gun. Just go gentle with the gun so you dont hurt the paint, the idea is to warm the metal above freezing.
Worst case scenario, a pry-bar WILL pop it, but count on replacing the seals. Had to do that once or twice in my life.
If it's not a deep freeze that would effectively weld the door shut, try using a plastic ice scraper to pry to door open. I've had to do this once or twice each winter for ages now and, if the ice patch is small, it can easily pop open the door without doing any damage to the vehicle at all.
Isopropyl alcohol, windshield washer fluid. Something that will combine with water and is below water's freezing point. Anything hot like lacquer thinner might eat the paint or rubber seals.
You can do it with a pot of warm water if it's not too cold.
Hot water and open immediately. Wipe it dry as you can and spray WD40 liberally on the seal all the way around. The WD40 displaces water. You also can use it on wet distributors and plug wires. I use this all the time on cars I have to pull in the garage that are frozen. I just did one this morning while it was 5* out. Washer fluid or alcohol work, but takes a while.
DONT pull too hard on door handles. Most newer cars have plastic ones. I cant count the number of door handles Ive had to replace from people trying to pull the door open. The plastic also breaks MUCH more easily when cold.
[This message has been edited by rogergarrison (edited 01-16-2018).]
It's like the frozen bolt. Tighten before loosening. Give it a good shot INWARD before attempting to open. I've had this work many times. The few times it didn't work it was because moisture had gotten into the foam insulation and that acted as a cushion that would absorb any movement without breaking the frozen seal.
Finally got it with hot water. Made it into civilization to get a bag of stock salt for the steps and back patio. People here buying little boxes of kitchen salt to put on their steps for $2ea and I buy 50 lb sacks for $4-$6 at any feed store. Usually have some but I mixed up some range meal last week and used the last I had.
It's like the frozen bolt. Tighten before loosening. Give it a good shot INWARD before attempting to open. I've had this work many times. The few times it didn't work it was because moisture had gotten into the foam insulation and that acted as a cushion that would absorb any movement without breaking the frozen seal.
This, most doors will give inward against the rubber, cracking the ice around the edges.