How can I get a grease stain out of a sweatshirt if its already been washed?

Try OxyClean. It worked on my favorite t-shirt. Just make sure to get the laundry version and not the household cleaner version.

Grease stains are oil based, oils are broken down by solvents/enzymes.

You need a solvent based cleaner as opposed to water based.

Not familiar with the products already mentioned (we have different ones in the UK), if they're solvent based they should work fine - check the active ingredients panel on the packaging.

Failing the above get it drycleaned. Dry cleaning is washing in a solvent, if that doesn't shift it then nothing will.

Fels Naptha. Sometimes it's hard to find, but, it will take out almost anything. You can find it where the body soap is in the grocery store. It comes in bar form in a white, red, and green wrapper. You can use it on any fabric as well. Just wet the spot and rub the bar over the stain, then rub it in, sometimes I'll let it sit for a few minutes, then wash normally.

I just removed a grease stain that had been "set" for months. I made a paste of Dawn and Baking soda, and applied it to the stain. I let it sit overnight and washed as usual.

"amaze" laundry detergent is actually amazing. run a shallow tub as hot as the water gets and throw your shirt in it flat, dump a little of the soap on the spot and wait ten minutes. rub the soapy material into itself until the stain is gone =)

I use "Shout Ultra Gel". It has a scrubbing brush attached, so you squeeze out the gel, scrub with the brush, let it set for a short time and wash. It's worked on any stains.

I've had some luck with cheap hairspray. Like Aquanet. It also gets out ink stains.

have you tried soaking it in napisan