That would be a good safety measurement, the viscosity compensation...
Our oil burner does have a little floater chamber to control the oil level, but that does only work with Diesel fuel or fuel oil.
With old oil, the floater chamber gets stuck with thick clods of sludge and other oil contaminations. We just use a manual ball crane to adjust the oil flow.
When it's about 0°C the oil is very thick. When you heat the workshop to 18°C, the oil gets thinner and may rush through the ball crane at double speed.
One day we had burning oil overflowing from the burning pit in the heater... Thank goodness that my brother was just walking around, smoking a cigarettte, and saw it... Otherwise our paint job would have been for nothing...
Our oil burner has the small burning pit in the center, about 20x20 cm and 10 cm deep. The sidewalls are made of perforated steel sheet, through the small holes, the blower blows fresh combustion air to the fire. it does not have a pump, dispenser or whatever, it just has a huge fan.
I think if you have an old plastic fan from a hog stable or something, and let this BLOW into the fire kettle this will work.
NOT if it sucks the air out of the kettle because the plastic fan will melt. In case of blowing into the jkettle you get an overpressure kettle that needs to be sealed or it will leak smoke into your workshop..