Pour point depressants are used to allow the use of petroleum based mineral oils at lower temperatures.
Wax crystals, which form at lower temperatures, may interfere with lubrication of mechanical equipment.
If the concentration of pour point depressant is too high, there may be a visible effect on viscosity at higher temperatures.
Non-refined oils contain polyaromatic hydrocarbons and resins which act as antagonists against synthetic pour point depressants.
Most commercially available pour point depressants are organic polymers, but nonpolymeric substances such as phenyltristearyloxysilane and pentaerythritol tetrastearate may also be effective.