Word forms: (regular plural) dilutions
(Automotive engineering: Fuels, oils, emissions, and other fluids) A dilution is a liquid that has been diluted with water or another liquid, so that it becomes weaker. ⇒ Engines in good mechanical condition will usually show a small amount of fuel dilution in the used engine oil. ⇒ Even engines in good mechanical condition will sometimes show a small amount of oil dilution in the sump. ⇒ Dilution of the lubricating oil by unburned fuel will reduce its viscosity and cause the rate of wear to increase.
Collins English Dictionary. Copyright © Harper Collins Publishers