In summary to roll the oil on an auto it takes certain conditions
always start with diesel
the engine must be at its temperature 90c
the oil must be between 70 and 80c
only at this moment transferred to the oil
the engine must be stressed (not famous in traffic and slowed down for a long time.
The purge must be done long enough, (6 km in my case)
the engine oil to be monitored if the level does not rise (dilution)
the fuel oil must be well filtered, deposited. to eliminate animal fat
a prewash pump or a system so that the vane pump does not cavitate, it is hard to suck oil through the fuel filter which is not very big.
To have oil to 80c it is necessary a good heater largely dimenssioné and for that it is necessary to eliminate the return to the resevoir and to put the system in loop.
apart from that it works well, for the good trip, to make 10 km better to stay in diesel especially if it is cold ..
Andre
After two years of using bi-fuel on two old nissan, with rapeseed oil from Chinese restaurant, I confirm 100% André's summary.