Nothing wrong with what was used and or brake cleaner. Quicker than most things that are sold as cleaners in our industry and more readily available. Oh and a darn site cheeper. If you use it and extract at the same time oil and similar spots will come out completely. If you just use the spray be careful as gravity can take the same spot farther into the textile that is soiled. Best, Dave.
P.S. As has been said it is nothing like wd40. wd40 works very well but needs rinsing considerably or it will become the problem stain.
Carb, injector and break cleaners are pretty much what we are already using. Better packaged though as so much easier to use......