Okay... so you should under no circumstances leave a pan with oil in it sit for over 3 months, but IF you for whatever REASON do...!
Then you'll find that what was once sunflower oil has transformed into tar. I tried hot water, I tried soap, I tried vinegar, I tried 100% alcohol, with both an abrasive sponge and a dish brush. It made the room smell like vinegar and alcohol and it made the sponge turn into a flat piece of cardboard and the dish brush into a tool of every mother's nightmare.
I found a solution...! I searched the far parts of my mind of knowledge and remembered my chemistry class, there I was sitting, hearing the answer to my worries... I did what can only be explained as counterintuitive, what only a madman would do! And I poured more oil into that damn pan, and I scrubbed.... AND I SWIRLED! THEN I POURED DISH SOAP INTO THE OIL AND I SCRUBBED FOR DEAR LIFE! ... okay I feel like I might be getting a bit too into it, so basically I added more oil to make the old oil more viscous and then I did the normal washing procedure. It gets clean after a few washes.
I found a solution...! I searched the far parts of my mind of knowledge and remembered my chemistry class, there I was sitting, hearing the answer to my worries... I did what can only be explained as counterintuitive, what only a madman would do! And I poured more oil into that damn pan, and I scrubbed.... AND I SWIRLED! THEN I POURED DISH SOAP INTO THE OIL AND I SCRUBBED FOR DEAR LIFE! ... okay I feel like I might be getting a bit too into it, so basically I added more oil to make the old oil more viscous and then I did the normal washing procedure. It gets clean after a few washes.