Whether you call it vehicle oil or engine grease, it’s one of the most challenging stains to get out. It is very helpful to start with a strong solubilizer/solvent that is appropriate for fabric. There are a few different degreaser products you can try — Goo Gone and De-Solv-It are the two I am familiar with—that are typically available at hardware stores. First you should check to make sure you can safely apply any product you want to try on your jeans with a quick colorfastness test:
- Apply a drop to a hidden part of the jeans, like the denim facing inside the front pocket.
- Wait one minute and then rinse and blot dry with a towel.
- If there’s no color change then you should be able to safely use the product on the jeans.
Assuming the jeans pass, then you can try the following:
- Work on the jeans when the stained area is dry; that is, don’t rinse it first!
- Apply the degreaser full-strength directly to the stain and rub it in, letting it sit for 3-5 minutes. This helps solubilize the oil and jumpstarts stain removal.
- Next apply a little liquid laundry detergent or liquid dishwashing detergent (the kind you use for hand washing dishes) and rub it into the stain; wait another 5 minutes.
- Now wash the jeans using the correct amount (don’t underuse!) a good detergent in the hottest water recommended on the care label. Definitely use the hottest water you can — the hotter the water the better the cleaning, especially for oily stain removal.
- Finally, let the jeans air dry. If any residual oil remains, you can repeat the treatment with a better chance of eventual success if the jeans have not been in a hot dryer.
I hope this is helpful — please let me know if you have any other questions, and thanks for writing.