Temparature effect on density
its because of the oils density
You need to specify the oil, since there are many oils having different densities. Some oils are less dense than water, while some oils are more dense than water. Motor oil has a density of about 0.876 g/mL ; while water has a density of about 1.000 g/mL.
There are different densities of oils used in cars. It's known as 'viscosity'. In engine oils this ranges from 5 to about 30. Some gear oils, as in back axles range up to 85 or more (this is very thick and dense)
Different oils have different densities; usually a bit less than the density of water.
Oil is heavier than water so it sinks to the bottom.
Fats (lipids) have the greatest calorific density, whether they are oils or animal fats.
density units are kg per cubic meter. if you reduce the weight, and reduce the size they cancel out, and the density is the same.
Density is mass/volume. So for a given mass as the volume increases the density will reduce.
Lubricant (Liquids, oils, grease, fats, water, graphite...)
Squeeze all the fat oils out of it and it's skin.
Density is mass/volume. So for a given mass as the volume increases the density will reduce.
One way to reduce the density of an object is to increase its volume while keeping the mass constant. Another way is to reduce the mass of the object while keeping the volume constant.