Pour point and pour point depressants
Pour Point Definition
The lowest temperature (in °F or °C) at which a motor oil remains pourable. Synthetic oils and lighter viscosity oils have a lower pour point, so they remain pourable at lower temperatures.
Pour Point Depressant
A pour point depressant is an additive used to allow a certain viscosity oil to remain pourable at a lower temperature. The pour point depressant additives inhibit the formation of wax crystal structures at cold temperatures that normally would prevent oil flow.
Pour point depressants are used mainly on conventional oil rather than synthetic motor oil because conventional motor oil contains paraffin (wax) and true Group V synthetic oil does not.