I have an oily sticky mark on my jumper and we have tried dabbing it with shampoo, dish wash detergent and wool wash. None have made any impression on it. I have no idea how I got the stain but it looks like my thumb size and maybe I had something on it when I took the jumper off.
All that I can think of is it maybe grease from a roast we had that night and I did the washing up.
292700cookie-checkOily stain on a cotton jumper
Get some Kenco from Bunnings and use it as a spot cleaner. Alternatively, if it is oven grease, sugar soap will work
https://www.drchemical.com.au/chemistry-at-home/how-to-get-cooking-oil-stains-out-of-a-cotton-shirt
Spray oven cleaner on it liberally (yes oven cleaner) and leave for a few minutes, rinse and repeat. the oven cleaner won’t damage your clothes at all.