Scrape as much grease as you can off the shirt with a spoon or butter knife. Rub liquid laundry detergent into the stain and let it penetrate for about five minutes. Wash the shirt in the washing machine on the hottest water setting. Repeat if necessary to completely remove the stain.
Spray oven cleaner on the grease stain and allow it to soak in for five minutes. Wash the shirt in hot water in your washing machine. Dry as usual.
Scrub the grease-stained shirt with Dawn liquid dish detergent, shampoo or Pine Sol cleaner by hand and let it soak for three to five minutes. Wash the shirt in hot water to remove the stain.
Treat older grease stains that have already been washed with Lestoil. Apply it to the stain and wash the shirt in hot water. Wash the shirt a second time to remove the strong Lestoil odor.
Sprinkle enough baby powder over the grease stain to completely cover the stain. Let the powder sit for at least 24 hours. Wash the shirt in hot water in your washing machine. Repeat if necessary.