Cleaning suede can be difficult because you want to avoid getting it wet if possible. That said, there are methods you can use to clean suede that require little to no moisture. When it comes to removing diesel fuel and other greasy stains from suede, the key is to absorb the stain. With a few things from your cupboards and some degreaser, you can do this on your own.
Apply cornstarch to the diesel fuel stain 1 tbsp. at a time. Put enough cornstarch on the stained spot to cover it entirely with a 1/4- to 1/2-inch layer.
Leave the cornstarch on the diesel fuel stain overnight or for about 10 hours. Shake, vacuum or brush the cornstarch off. It should have absorbed the fuel.
Prepare the item for the use of leather degreaser if the stain is set in or if the stain does not lift off with the cornstarch. Protect every part of the suede that is not stained with diesel fuel by covering it with paper. Use a large piece of paper in which you cut a hole that exposes just the oil-stained area.
Hold the leather degreaser can about 1 foot away from the stain and spray it by moving the can back and forth in even strokes. There should be an evenly applied layer of white powder left on the surface of your suede.
Allow the white powder from the leather degreaser to dry, then vacuum, brush or shake away the powder. Reapply if the stain is still present.