20W-50 is probably way too thick for your winter. Best would be to change it to a grade that is appropriate for the temperature (check your owner's manual or service manual).

Unfortunately, your oil is WAY too thick: 20-50 is not recommended at all. For winter use, 5W-30 is best; summer: 10W-30. However, now that you are stuck, take the easy way out and buy a dipstick heater which is a simple drop-in to the dipstick. Heat the oil, remove the heater, and start the car. An alternative is an electric heater that sticks on the oil pan. In both cases, you need to remove them before driving.

Well, it might start. I'd go ahead and try before I assume problems.

The oil will be stiff. But, if the engine will turn over, I think it will probably start.

Battery is a little old. Die Hards, even old ones, have done right by me.

Easiest block/oil heater is the 'dipstick' variety that can be had from most auto parts places for a few bucks. Probably less than $10. Used one for years in Minnesota on old pickup trucks. It replaces the oil dipstick and warms the oil when plugged in. It works on 110V from a wall socket. They come in various lengths, so pick one that is approximately the same length as the dipstick in your car.

If you have a 'trouble light' or a light bulb on a cord that can be put inside the engine compartment, near the battery, it will warm the battery. If the light bulb is in the engine compartment long enough (hours) it might warm the engine block enough to help. Use the biggest bulb you have, 60W or larger, and perhaps even cover the engine and battery with a blanket with the light bulb under the blanket.

There is a possibility of fire any time you put something hot, like a light bulb, inside the engine compartment. But the use of a little common sense and a little space, like a couple of inches, between the bulb and anything else should be safe enough. Be wise, and be careful if you do this.

Jumping the battery, even with thick cables, from another car is a sort of last ditch effort. If you need to do this, connect the cables and let the running donor car charge the battery in your car through the cables for a while. 10 minutes would not be too long. That will warm your battery and give it a good charge. In reality, most of the starting current will come from your battery anyway. The jumper cable clamps do not make a connection good enough to provide much of the 100 amps or so the battery will have to source while the starter is turning.

Be certain the jumper cables are connected correctly. Reversed connections between the cars will almost certainly destroy at least one of the batteries and perhaps the charging system in one of the cars. Be wise, and be careful.

It may also be wise to clean the battery cables and battery posts before you try the jumping thing. Sometimes, just making sure the cables, clamps and posts are all clean and tight will be enough to get a start on a cold day.

If your car is a manual, put it in neutral first and keep the clutch depressed while starting. If it is automatic, it won't make much difference whether it is in park or neutral.

Good luck.

91-240, no longer in Minnesota.

Oil should be light enough for 0F.

I've heard that running the parking lights for a couple of minutes before starting the battery actually causes the battery to warm a few degrees, and the increased temperature does more good than the extra power use hurts, resulting in a better chance of starting. I don't know if I believe it. It would be an interesting experiment.

There are an array of block/water/oil heaters that will keep the oil thin and add heat under the hood to help the battery stay warm. However, if you are on a limited budget and you don't want to do any invasive mechanical work in the cold, a regular blanket would help keep a little of yesterdays's engine heat under the hood, if the car is garaged. If it is outdoors in the wind, this probably won't help. DON'T forget to remove it before starting the car!

You could probably use an electric blanket under there, though I question how much more good it would do.

Finally, those jumper cables may come in handy. There are tables for the percentage of battery cranking power that is available at low temperatures. At some temperature, between the thick oil, cold heads, and cold batteries, it takes two cold batteries to start one car.