All motor oils have to do four tasks for an engine to run right with adequate power. It has to lubricate. In a non-running engine oil tends to run into the pan. On start up it has quickly form a film between moving parts to reduce friction. This increases power, performance and efficiency. Oil has to protect. The film protects against wear. The oil also has to keep the engine free of corrosion. During the life of the oil it’s subject to heat, water condensation and by-products of combustion. These all cause acids that oil by design resists. Oil must clean. Particles in the engine can reduce fuel efficiency and performance. Particles larger than five to twenty microns will cause damage. Lastly oil must cool. Anti-freeze cools only the upper engine. Motor oil cools the rest.
Motor oils are not created equally. There are basically two types, petroleum and synthetic. Synthetics outperform petroleum in all four tasks. Petroleum base stocks have contaminants within them breaking down quickly. This results in coatings of varnish, deposits and sludge. The remaining oil is thick, pumps harder and has minimal heat transfer ability. Petroleum oil molecules vary in size. The heavier ones tend to hang on metal surfaces and keep heat from flowing into the oil stream. This increases friction which increases wear. Petroleum oils have wax or paraffin in them that thicken in cold. On cold winter starts petroleum oils may leave the engine unprotected and vulnerable to wear until it warms up. Where petroleum is adequate synthetic is superior. Synthetic molecules are of uniform size and weight and free of any contamination. They function with less heat and friction. More base stock equals longer oil life. Synthetics have more lubricant base stock than petroleum. Petroleum oil needs additives so it can function as a multi-viscosity oil and maintain viscosity at high temperatures. Synthetics are more heat tolerant.
Synthetics on average are forty degrees higher than the petroleum average. On cold starts synthetics coat immediately, some leave a thin film on metal at all times. This minimizes cold start wear and reduces battery draw.
Synthetic oils offer extended oil drains, extended vehicle life, reduced repairs, improved fuel mileage and performance. Make sure you use a long drain filter with synthetics. They have better media to absorb larger amounts of dirt and should have an anti drain back valve and fully tucked seams.