I'm assuming that the patio is stone or cement.
Fuller's Earth is pretty good with oil stains. You get it in cat litter (not the wood stuff !)
Spread it thickly over the stain then give it several hours to absorb the oil.
Remove it and re-apply until the stain has gone...or at least gone down a bit.
Good Luck
As a last resort, if removal proves impossible, you could consider coating the whole of the patio with teak oil. At the very least, you'd have a uniform finish with no stains showing!
I found that in a sunny area the stains soon disappeared.
I only had myself to blame although I have felt at times like digging a big hole & throwing myself in... :o)