What is a good detergent or stain remover that can remove grease on a tshirt?

i tried using bleach but maybe its the way im using it but its not workin out.

Dawn dishwashing liquid. Just rub it on the stain, let it set about a minute & wash as usual. Dawn cuts the grease.

The first thing I do with stains is to try washing up liquid. Its a de-greaser and a small amount dropped on the stain and gently rubbed often works. Leave for about 30 mins and then wash.
The problem could now be if you have tried other methods and then washed the garment the stain will be set in the fabric.
You might need to buy one of the stain removers like Stain Devils and hope it helps.
Good luck

First start with a dab of dawn dish soap, then spinkle on top of that baking soda and scrub with a toothbrush. Wash normal, should come right out!

depending on the grease,
use a grease cutting liquid dishwashing detergant. It gets most of the lighter greases out.

if it's a heavier grease, like axle grease, you need a commercial grease cutter and a really good laundry detergant.

A good stain remover is Shout

Washing up liquid on the stain should take the grease out in the wash. It works on the grease like normal washing powder doesn't.

May sound a little odd, but try putting a can of coke in the wash. It eats oil away

dishwashing liquid; it's made to break up grease. You can also sprinkle some talcom powder or corn startch on the stain if it didn't come out in the wash. Leave it on there for many hours or even overnight then wash again. The powder soaks up the grease. The stain should be completely gone!

tide marker thing
spray and wash

Dawn dish soap