You could grab like 1 or more pieces of paper, stacked together, and make your own funnel/backboard like mechanism.
If you have cardboard paper, I'd use that, since it's stronger.
You could use tape to make something very much like the shape of a plastic funnel, or you could just hold it together with your hand.
Then when you're done, just throw the paper in the trash.
lifehacks.stackexchange.com/users/143/CRABOLO
You can make a funnel yourself out of a plastic water or soda bottle
you may have sitting in your car.
Using scissors, a knife, or even your teeth, you can rip through the water bottle and make it look like the image below.
Source: wikiHow
lifehacks.stackexchange.com/users/20/michaelpri
Pouring quickly helps, but if you hold the container close to the hole you are pouring it into it should work.
Alternatively Making a Aluminium foil funnel should work.
You may opt out of using foil though and cut the top off a water bottle and pour the oil that way.
Also, the plastic and foil may last longer than a paper or cardboard one.
lifehacks.stackexchange.com/users/188/Pobrecita
Modern plastic 1 quart oil bottles have the funnel built in.
In the old days of one quart cans of oil, you either used a spout or opened the can with a can opener and poured into a funnel.
You will note that on a modern oil container the spout is offset to one side.
The design is meant to place close to the oil opening of the engine and once started you simply tilt it up vertical inserting the spout into the opening.
While the use of a funnel may be necessary on some engines because of an awkward oil cap placement, generally speaking using a funnel to add oil is reinventing the wheel, and will cause more mess and problems then it solves.
lifehacks.stackexchange.com/users/117/Jon
the other answers are good but also to help reduce the glugging, therefore the increases the accuracy, pour it so half
the pouring hole has oil flowing through it.
this can be done by tipping the bottle slowly or by turning the bottle so that the longest edge of the bottom parralell with the ground.
gluggs-----|
| dosnt glug| | |`````````||_o_| |_o_______|
lifehacks.stackexchange.com/users/15794/Topher Brink
A gas station will give you a disposable paper funnel (they look like these: https://www.freshwatersystems.com/p-9496-1000-konie-10-oz-disposable-paper-funnels-8-sleeves-of-125.aspx ).
Use the right tool for the job, don't try to create a makeshift funnel unless it's your option of last resort.
lifehacks.stackexchange.com/users/110/Jon Leibowitz
Say the oil light turns on in my car, so I check the dipstick and it's low. I have an extra quart in the trunk...  ...but I don't have a funnel to pour the oil through.  I once tried pouring straight from the bottle, but since it was a windy day, oil went where it shouldn't have. How can I pour  all  the oil into the engine?
How can I add oil to a car without a funnel?
lifehacks.stackexchange.com
<substitute-tool><car><liquids>
lifehacks.stackexchange.com/questions/493
lifehacks.stackexchange.com/users/15/Mooseman
You could try making a make-shift funnel using pieces of paper, aluminium foil or a plastic water bottle. Alternatively, some new bottles have a funnel included, and some gas stations will provide you with a disposable funnel. The options are to try making a funnel out of paper, aluminium foil or a plastic bottle, to get a modern oil container with built-in funnel or to get a disposable paper funnel from a gas station.
Try making a funnel out of pieces of paper. Try making a funnel out of a plastic bottle. Try holding the container close to the hole and pouring quickly - or make a funnel out of aluminium foil. The modern plastic 1 quart bottles have a funnel built in so this should not be a problem. Get a disposable paper funnel from a gas station - makeshift funnels generally don't work well.