What is Viscosity Index Improver Multi-viscosity motor oil is formulated with thin base oil which is fortified with viscosity index improver (VII) additives. The base oil is thin enough to pump and flow well at cold temperatures and the VII allows the oil to thin less when hot than it normally would without the VII additive. How does VII work? VII additive is complex polymer molecule that is coiled and spherical in shape at cool/cold temperatures. As the polymer heats up and is pressurized the molecule deforms into a long … Read More

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