The solubility of oxides and other ceramic powders depends on what the solution and solvent should be. Temperature is also important. For example one definition of glass says that it is solid solution of natrium oxide, kalium oxide and silicium oxide. many kinds of steel are similarly defined as "interstitial solid solution of carbon in alpha-iron", etc.
As for the solubility of metal oxides in water, it is close to zero. The same for alcohols, ethers, alkanes, etc. The usual way of getting metal oxides into liquids is to mix suspension so fine that the powder will be hard to separate due to the brownian motion and such. Today you may order nano-powder as well.
Now to the point why somebody asked this: the cerium oxide is inert. The point when it becomes interesting is at higher temperatures when it can oxidize carbon for example at temperature much lower than the carbon will usually burn. Another useful property is that it will reduce nitrogen oxides and take the oxygen to form its ceric oxide state. This is used in car catalysts due to good efficiency and favorable price. Yet another use - which can be derived from wikipedia information already is chemical reaction with laughing gas - N2O to form really strong, orange oxidiser (forgot the name). I plan to test it in a rocket engine fuel soon.
Just to note - many combustion processes, whether in furnace, cars, rockets can not be enhanced, taken more power from them, because of the limited speed of reaction. That is where catalysts take place. Ceric oxide can act as a catalyst. When reacted with certain nitrous oxides it can take form of another chemical composition which acts as a strong oxidiser potentially increasing the speed of the reaction even further.
The maximum surface area of ceric oxide nano-powders ranges from 35-70 square meters per gram of the powder. Ordinary polishing powders do not have such large surface area since they are aimed for polishing, not as a catalyst.
P.S. if you really want more answers than this, ask me at http://zumotor.blogspot.com/
Endothermic substances.
Cerium sulfate is a very strange compound; increasing the temperature the solubility decrease.
The solubility of cerium sulfate in water at 30 degrees Celsius is 114 g/L. To make a saturated solution in 100 ml of water, you would need to calculate the amount of cerium sulfate that can dissolve in that volume at that temperature. This would be approximately 11.4 grams of cerium sulfate.
The solubility of cerium sulfate at 30°C is approximately 117 g/100 mL of water. To make a saturated solution, you would need to add at least 117 g of cerium sulfate to 100 mL of water at 30°C.
Some examples of solutes that do not dissolve when warmed include lead sulfate, barium sulfate, and strontium sulfate. These compounds have low solubility in water and do not readily dissolve with an increase in temperature.
Cerium hasn't odor.
Cerium is a soft, malleable, and ductile metal with a silvery-white appearance.
Cerium was not known by alchemists.
Cerium is a solid at room temperature and pressure.
Cerium is a silvery-white metal.
The cation of cerium is Ce(3+).
Cerium is reactive but not highly reactive.