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The function of Pour-Point Depressant (PPD) is given in the name. They depress pour-point by inhibiting the waxy structures that form in mineral oil at low temperature. But for modern engine oils pour-point has little relevance and isn't included in modern international engine oil standards. Industry experience over the decades has replaced pour-point by other more valid assessments of an engine oil's suitability at low temperature. In particular low temperature pumpability by Mini Rotary Viscometer (MRV) due to its inclusion in SAE J300 is the primary test. In some cases this is now required on used oil, and most recently in Europe on oil oxidised in the presence of biodiesel by CEC-L-105-12. However PPDs exist or have been developed which are effective in these evolved low temperature requirements of engine oils.

The new ILSAC GF-4 specification for Passenger Car Motor Oils includes a measurement of low-temperature viscosity after the Sequence IIIGA engine test. The measurement is conducted according to ASTM D 4684, the well known TP-1 MRV (Mini Rotary Viscometer) procedure. While the limits are the usual values found in SAE J300 which are no measurable yield stress and 60,000 mPa.s maximum, it is tested five degrees Centigrade warmer than called for by the fresh oils' SAE W grade. The need for this new measurement and specification is based on the finding that some PCMO lubricants' low-temperature/low-shear rate viscosities, but not necessarily their higher temperature rheological properties, were seriously degraded in severe oxidative environments.