couple of gluggs in your prespray should do the trick,
if i have an oily job i'll put a few gluggs in some powerburst prespray, then spray the carpet and agitate with enviro, as i'm agitating if i see any black marks that won't come out and i know there grease or oil based, i'll squirt them with Citra Boost mixed 1 to 3 in its own bottle, (hot if its a new mix but cold seems to do just as well) then go over again with agitation machine and that usually breaks the stain up. then rinse with an acid rinse.