used oil

To obtain the Specific Gravity of the oil, you can test some.

But I am thinking that your mixtures of used oils will vary, from drum to drum.

Therefore to get an accurate measure/estimate, the composition of oils in each drum needs to be known, so you can work proportionally from Tables.

Refer to the earlier website given:

http://www.simetric.co.uk/si_liquids.htm

Automobile oils 15 C 880 - 940

Look further down in that table, to estimate other Specific Gravities of Oils:

Hope that helps you.....

No, there are always too many contaminents and diluents. Specific gravity (SG) can be measured with a hydrometer for light liquids, ie for liquids with a SG less than one.

If you need accuracy, remember to correct the oil sample to a reference temperature, or heat/cool to obtain that temperature in the sample.

Note that the hydrometer will not work as representing the correct S.G. = Specific Gravity unless the oil mixtures are constantly stirred.

If the oil mixtures are allowed to remain in a container, over time the lighter fractions = lower S.G. oils, gradually come towards the surface.

This means if you draw off a sample in a hydrometer, it only gives you the S.G. of that top lighter layer.....

Specific gravity usually ranging from 0.95 to 1.03 it is much heavier and more viscous than No. 2 oil, kerosene, or gasoline. No. 6 oil must, in fact, be stored at around 100°F (37.8°C) heated to 150°F (65.6°C)–250°F (121.1°C) before it can be easily pumped, and in cooler temperatures it can congeal into a tarry semisolid. The flash point of most blends of No. 6 oil is, incidentally, about 150°F (65.6°C). Attempting to pump high-viscosity oil at low temperatures was a frequent cause of damage to fuel lines, furnaces, and related equipment which were often designed with lighter fuels in mind.. Stored in tanks, it must be heated especially in colder climates if you are pumping it. If you are using it to burn as fuel, it must be atomized at the burner. SPEC oil, and or waste oil is oil that is used and has been processed. This is oil pumped from oil/water separators usually associated with maintenence garages. The oil is pumped out of the oil/water separator and taken to a recycling plant, or waste oil plant. The process first invloves filtration for small machine metal parts associated with diesel and gas engines. The filtration through bag filters are usually in the 400 and 800 micron range. After filtration, glycols and water must be separated. Stored in heated tanks, the water is burned off and or drained due to their natural separation properties from each other. The result is SPEC oil or #6 oil.

Cant you just get a good approximation of the density by obtaining the oil (or mixtures) weight in grams for a specific volume (say 100 ml)?

If you are just looking for an estimate of the Spec. Grav. of oils perhaps Nelson's "Petroleum Refinery Engineering" (McGraw-Hill) is a good source.