Ripstop nylon is a fabric commonly used for camping equipment, outdoor clothing like jackets and pants and even parachutes, kites, sails and banners. It is water-resistant and is also quite strong against rips and tears, making it good for wind activities. Most ripstop nylon is made of nylon, but it can also be interwoven with other fabric threads including cotton, silk and polyester. These other fabric threads can retain stains, making it more difficult to get them out than with regular nylon. You may be able to determine if your jacket has other thread types in it by looking at the label; if not, proceed with removing your oil stain from your jacket.
Apply grease removing dishwashing soap (not for the dishwasher) directly to the stain. Rub it in with your finger and allow it to set for about an hour. Rinse with the hottest water your fabric can stand (read the label to find out). Unlike a protein stain (blood or milk), oil responds to hot water because it loosens and "melts" in it.
Rub 1 tsp. (or as much as you need, depending on the size of the stain) of baking soda or baby powder onto the oily stain and leave for an hour or two. These substances will absorb much of the oil. Rinse the fabric with very hot water. You may need to apply dishwashing detergent to the remainder of the stain afterward and then rinse with hot water again.
Place 1 tbsp. of regular shampoo onto the oily stain as soon as possible. Rub it in gently and then rinse with very hot water.
Use a laundry detergent pretreatment spray or stick on the stain. Leave on for up to a day. Wash as usual. If this does not work, try using shampoo or dish detergent on the stain and rinsing again with very hot water. Be sure to inspect the stain before drying in a dryer. Putting the fabric in the dryer will further set the stain.
Boil some water and place your jacket in the sink (test for colorfastness first). For a very stubborn oil stain, pour about a cup of boiling water directly on the stain. The extreme temperature of the water should loosen the stain enough to be rubbed out with dish detergent or shampoo.
Spray a severe chemical treatment on a set-in or very stubborn oil stain. Apply the chemical only to the stain. You'll want to spray a small, hidden piece of your jacket nylon first before applying anywhere that will be seen to make sure it will not damage the fabric. Rinse the chemical out thoroughly according to the manufacturer's instructions.