It depends on the composition DTcrosswordfan.
Many years ago when I was a student taking my first chemistry degree, I worked in the lab of a major UK Oil Refinery. The refinery produced "heating oil" and it left the refinery in tankers en route to customers. Hourly production samples were taken of all distillates produced and heating oil was deemed satisfactory if it fell within a certain SG range. There is no set SG for it as it's in essence a very crude mix of a number of distillates.
See the SG quoted in Section 9 on the following link as you should see that the same applies nowadays.
http://www.celticfueloils.co.uk/kerosene/