Now you can "expect to get all the grease out".
For small localized spots: Spray the spot with "easy Off Oven Cleaner". Get the version that is nasty, contains LYE and you can't breath. That "pleasantly scented" version is crap. LYE: the mechanic's wife's friend.
For big spots or lots of clothes: Fill the washer to its low level where the agitator paddles are just covered. Add a cup of LYE, Plumbers or Red Devil, and let the machine agitate for just a few seconds to mix. The mixing is to placate you into thinking you are being carefull. You can also just drop in a small load, (that IS important), set the temp to HOT and dump in the LYE. Now look, if that lye can eat thru a grease clogged drain in a Chinese restaurant in a new york minute or dissolve baked on grease on an oven, it can find and destroy motor oil on a shirt. I know, I know, what does that do to the fabrick? Not a thing. Next nay sayer: but what does that do to the washer? I must have used this in ten washers and nothing was ever damaged. and the finale, but won't it leave a ring in the washer? No evidence of that ever happening either.
For diff grease soaked rags I put them in a 5 gallon bucket and added 2 cups of LYE, poked at them with a stick for a few min and let them get acquainted over night. Dumped that in the washer the next day and set it for HOT" , "NORMAL" and double rinse. Wall Laaa, all better.
You will want to follow up with NOTHING ELSE BUT TIDE wash cycle.
Now you know that I wouldn't be this emphatic if I weren't absolutely sure. Oh, and, don't drink even a little bit of that wash water.
John the chemist wanna be