fcrist
There are some engines that run off of well head gas, but not off the crude that I know of.  I wish I could remember the term for that type of engine but it is not coming to me right now.  Maybe someone else can help you with that.

StoneCold

I believe that some crude oil pipeline pumps are driven by diesel engines burning the crude from the pipeline. Can anyone confirm?

HAZOP at www.curryhydrocarbons.ca

Fcrist:

Contact Sulzer, MAN and Pielstick.......they among others can give you some guidance with crude-burning slow and medium speed diesels.

Orenda

StoneCold, the engines you are thinking of are called "Hit & Miss" http://www.zmwilliams.com/

Stone Cold- I called the type of reciprocating engine you refer to as a gas engine, and bought a couple from a subsidary of Dresser running of the off gas to drive a triplex pump for a downhole jet pump.  Lovely little self contained artificial lift project!

Yes, there are such engines on the market (medium speed), but it depends on the spec of the crude oil.
There are several power stations in the oilfields of Sudan and Equador (and also pumping stations) running on sweet crude.

Take a look at www.wartsila.com

I used to work at Rolls-Royce Bergen, former Bergen Diesel.
We delivered some crude oil engines to Sudan a couple of years ago.
The engine is basically the same as your common medium speed diesel, the ones we supplied were 320mm bore, and 360mm stroke, running at 750 rpm.

Crude oil places lot of wear on the injection equpiment, so nozzles and injection pumps must be replaced more often than usual. Apart from that, the engines runs as well as on heavy fuel.

According to

http://www.steamengine.com.au/ic/engines/vapour/

just about any spark ignition engine can be run on at least crankcase oil by preheating to the point of vaporization, which i would think to be somewhere close to crude oil.

The whole page is interesting, but for the specific part i'm addressing, search for fordson on the page and read on from that paragraph.