Sump oil and diesel would probably work, but getting something to grow there afterwards might be a problem if too much is used, especially if the plant covers a large area.
If you are keen on getting rid of it and don't feel up to digging it up a mixture of Kamba M (relatively low toxicity) and a couple of DROPS of dishwashing liquid should do the job. It's less toxic than the 2,4, D derivatives and will also no harm the grass. But no matter what you get, Read The Label. (
Sorry
The Hort teacher coming out in me
)