How can I get black grease out of a carpet?

You can dye it with fabric dye. Tutorials on YouTube

I haven't tried this on grease spots, but it really works on other spots: 1/2 cup blue Dawn and 1 cup hydrogen peroxide. Mix in a spray bottle, spray spot, let sit 2-3 minutes. Scrub gently with light-colored cloth (if fabric is light) and blot area with dry cloth. If fabric feels soapy, blot area with wet cloth, then dry one. Let dry. This cleaner can be stored for another use.

I would start out with shaving cream rub it in a little and let soak then blot it up with paper towels then you can go further with whatever you decide to do ?

I would use Dawn & baking soda

Ronson Lighter fluid is the chemical that carpet cleaners use. I have used it and I have used Goo Gone as well.

My mechanic gave me a can of brake fluid cleaner to take grease out of carpet. You need to have good ventilation, just spray greasy areas and blot with a white cloth. Make sure to blot or rub towards the center of spot. My husband brought something greasy home from work and everything else I tried didn’t work, to the point of ruining the nap of the carpet. This took it out, also an old stain of unknown origin... gone! Just lay clean dry cloth over area after cleaning so it can dry completely before walking over it.

If it is still greasy put corn meal on it & let sit over night under a white towel. Vacuum in morning. If not greasy spray some water on it first then apply corn meal let sit overnight then vacuum. May need to do it a few times as it will slowly wick the grease up, but it should be the first thing you do. Never rub you just make it go deeper & spread out. Using other products may set it in. My hubbys a carpet steam cleaner. His regular customers call before trying things on their own - which is a natural reflex. He usually tells them what to do without charge or visit but they are regulars. Good luck to you.

If you use what everyone suggests do a test sample in a closet. Put some grease down and after a bit try things out. But corn meal will not ruin it. Either it works or it does not. Also the age of the stain & if it is in a traffic area can make a difference.

I'd try blue Dawn dish liquid mixed with lukewarm water begin blotting the stain. I would avoid rubbing because you could spread the grease stain or spread deeper into the pile. Start with nontoxic chemicals first.

You could also go to your favorite full service dry cleaners and show them the photo and get their advice.

Try a product called oil eaters, you can find it on Amazon.

Get a cleaner degreaser from the auto store if Dawn Platinum and white vinegar does not work.

Go with the Dawn dish liquid and hydrogen peroxide. Blot from the outside in so not to spread the stain any further. You can also try WD40 also blotting from outside in. Rinse with clear water.

Lestoil gets grease out of anything. My husband had his bike in our den and left behind a 14” long grease mark. The carpet is forest green and it literally dissolved the grease. Use dish soap and water afterwards and it’s good as new. Works on grease stains on clothes as well. Pre-treat and wash as usual. Works great!

WITH COOKING OIL..pour and scrub until much is gone..add Dawn and water...scrub...ALLL GONE!!!!!!...i KNOW...

Here's some information that might help you that should help you https://chascrazycreations.com/carpet-spot-remover-with-2-ingredients/

Before reaching for the nearest bottle of cleaning solution, keep in mind that the best carpet cleaning solution is often water. Blot (don't rub) the stain with a clean, slightly damp white cloth.

If plain water doesn't work, move on to a carpet stain remover or DIY solution. The best carpet stain remover will be tailored to what caused the stain.