The droid must become a force vampire.
He finds force sensitives and drains the midichlorians out of them to put them directly into his oil stream.
Also, Yoda pretty much said the force exists in all things. If it exists between a rock and a tree, why can't it be in a droid?
The force Exists in the droids parts, but the Droid does not have the ability to have a Symbiotic relationship with the midichlorians that would allow him access to the force.
Do not confuse the "Force" with the "Midichlorians".