There is no "leftover" fuel. Most of the additional fuel used in the regen process is burned in the DPF, with a very small amount of fuel getting past the piston rings and into the oil. The oil getting past the rings seems to be mostly an issue with regens that occur at low speeds like city traffic. Regens during high speed operation and particularly loaded / towing operation don't seem to let much fuel past the ring.
A forum community dedicated to Diesel engine owners and enthusiasts. Come join the discussion about performance, builds, ecodiesel, towing capacity, modifications, classifieds, troubleshooting, maintenance, and more!