Synthetic oil and synthetic blends

Synthetic lubricants were invented initially for high temperature gas turbine/jet engine applications where traditional mineral-derived lubricants provided inadequate performance. In the mid 1970s, synthetic motor oils were formulated and commercially applied for the first time in automotive applications. Improving the efficiency of lubricants, synthetic lubricants made wear and tear on gears far less than on the former petroleum based lubricants, reduced the incidence of oil oxidation and sludge formation, and allowed for extended drain intervals. Today, synthetic lubricants are used in modern day automobiles to lubricate nearly all lubricated components often with superior performance and longevity as compared to non-synthetic alternatives.

Instead of making motor oil with the conventional petroleum base, the molecules in the synthetic oil were artificially synthesized polyalpha-olefins, which are polymers specially designed to have improved motor oil properties. These polymers are made by bonding together alpha-olefin monomers which provide numerous flexible branching groups on the polymer molecule's backbone. Because this side branching interferes with the ability of the molecules to line up compactly next to each other, the flexible molecules can slide past each other more easily and the synthetic oil has good flow ability even at low temperatures. The molecules could be made large enough and "softer" to retain good viscosity at higher temperatures, yet the side branching interferes with solidification and therefore allows flow at lower temperatures. Thus, although the viscosity still decreases as temperature increases, these synthetic motor oils have a much improved viscosity index over the traditional petroleum base. Their specially designed properties allow a wider temperature range at higher and lower temperatures and often include a lower pour point. Because the viscosity changes much less with temperature, these synthetic oils need little or no viscosity index improvers that are used with the traditional petroleum based oils. The viscosity index improvers are the oil components most vulnerable to thermal and mechanical degradation as the oil ages and wears out. Because these synthetic oils have little or no viscosity improver content, they do not degrade as quickly as traditional motor oils. However, they still fill up with particulate matter like the conventional oils do, so the oil filter still fills and clogs up with time and must still be changed periodically. Synthetic oil still needs to be changed periodically; but some synthetic oil suppliers suggest the intervals between oil changes can be longer, sometimes as long as 10,000 - 15,000 miles between oil changes. The same SAE system for designating motor oil viscosity applies to synthetic oils also.

Tests have shown that this fully true synthetic oil is superior to conventional oil in many respects, providing better engine protection, performance, and better flow in cold starts than petroleum-based motor oil. Until recently the price difference between petroleum and synthetic motor oils was significant, however with the recent rise in the cost of petroleum the gap is closing. Since some companies of synthetic oil warrant their oils for extended drain intervals, then in the majority of situations synthetic oil actually saves the end consumer more money. Synthetic blend oil is a blend of full synthetic oil and conventional petroleum-based oil, a compromise between full synthetic quality and economy. The cost is intermediate between full synthetic oil and conventional oil. The benefits of synthetic oil are at least partially provided at a lower cost per oil change to the consumer.