Oil Stains on Interlock

Moving out of my house soon, like to get my damage deposit back without a fight. The main issue I have is the slow leak my jetta let go on the interlock. About 20-30 drips over the year I have lived here. I read about a few products, and washing methods and wondered if anyone here had experience with the job. So far my best option, without buying a pressure washer, looks like rubbing the stain with diesel or gas, waiting 10 minutes, and taking a torch to it. Open to any other ideas. Prefer not to waste money on "magic" but if you have used something personally and it worked, let me know.

Dawn dish soap. let it sit for 20 minutes then scrub with a brush

How does an interlock relate to this?

i pulled a head off a filthy diesel in my driveway and spilled some oil on the driveway. like a 1 foot stain. soaked in for like 2 or 3 weeks while I got the car back together.

soaked in simple green. scrubbed. soaked. scrubbed. soaked some more... about 3-4 hours and the filthy soot-filled oil stain is much reduced in appearance. I expect the sun will take care of the rest and sweat it out. it's now barely noticeable and I try to not park overtop of it now so the sun bleaches it out.