Is It Possible to Add Oil to Diesel Fuel?

Rough running of an engine can be caused by different reasons.  The first one is injection timing control disturbance.  The second one is incorrect operation of the fuel equipment.  In both cases it is advisable to visit a service station and have the car examined by specialists.

Another possible reason of rough running is refueling with low-cetane fuel.  This parameter characterizes the ability of diesel fuel to combust.  In case of using low-cetane fuel, the time interval prior to ignition increases.  This will cause the greater part of diesel fuel to be in the combustion chamber before the ignition.  This results in flashing of combustible mixture throughout the combustion chamber volume, causing a sharp jump in pressure inside the cylinders, making the engine work roughly.

In order to understand how to deal with the problem, you must first identify its causes.  One of the reasons for fuel lower cetane number is its dilution with other petroleum products (kerosene, gasoline, etc.).  Most often it occurs in the cold season, when it is necessary to ensure the reduction of pour point.  And what happens if, for example, diesel fuel is diluted with engine oil?  In this case, the cetane number of diesel fuel increases.  If the softness of the engine running was the only issue, it would be possible to say that adding oil into fuel is justified.  But it is not so simple.

There is no agreement of opinion in this regard among the automotive industry experts.  The opponents of adding oil into fuel note that most modern fuel manufacturers exclude the possibility of dilution of their product at an early stage of production.  Be it an additive, gasoline, kerosene or oil.  Although sometimes they make exceptions for their own-produced additives.  This is understandable, since nobody wants to lose money on their products but earn as much as possible.  Another argument against the dilution of diesel fuel with engine oils is a discrepancy in amount of additives.  Typically, two-stroke engine oil originally contains fewer additives than diesel fuel.  The difference in operating temperatures leads to an increase in the intensity of soot formation and reduction of the speed of its burning out.  The products of incomplete burning of motor oil and ash clog the nozzles and accumulate on the surface of the turbocharger components, in the catalyst and in the particulate filter.

Furthermore, an excessive amount of oil added to diesel fuel will inevitably lead to unreasonably high cetane number, which is fraught with the drop in engine power, increase in fuel consumption and smoke emission.

But there is also the opposite point of view, which allows adding engine oil into diesel fuel.  But here, there are several alternatives.  Some experts admit the addition of oil into fuels for older engines with pintle-type nozzles, while such practices are not considered acceptable for diesel engines with multi-hole spray nozzles.  Some experts justify adding of oil only in the cold season, especially in the case of its previous dilution with gasoline, kerosene, etc.



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